Biomedical subjects

R C Smith

Publications and source records attributed to R C Smith.

At least 181 records · Page 10Linked to original sources

PubMed1992

Accurate compartment pressure measurement using the Intervenous Alarm Control (IVAC) Pump. Report of a technique.

This study demonstrates the accuracy of a common, readily available pressure transducer system (IVAC pump) for the measurement of compartment syndromes. An in vitro assay was used to compare the accuracy of the IVAC pump manometer with the Hewlett-Packard monometer (HP78532B) and a miniaturized digital fluid pressure manometer (Stryker). The IVAC pump was accurate within 2.4 mm Hg difference of the HP78532B and Stryker manometers. Twenty-five patients suspected of having compartment syndrome posttibial fracture had compartment pressures measured using the IVAC pump. In all the patients, compartment syndrome was accurately assessed (positive in one case and negative in the remainder). The IVAC pump is readily available in most hospitals. It is easy to use and provides accurate measurements of compartment pressures.

Compartment Syndromes↗

PubMed1992

The effect on protein and amino acid metabolism of an intravenous nutrition regimen providing seventy percent of nonprotein calories as lipid.

BACKGROUND: The purpose of this study was to determine which peripheral intravenous nutrition (IVN) regimen, one containing 70% nonprotein calories as lipid IVN or one containing all nonprotein calories as glucose IVN, was most effective at reversing some effects of surgery on protein metabolism. METHODS: Twenty patients who required IVN after operation were randomized into two well-matched groups that received 36 kcal.kg-1.day-1 glucose IVN or 37 kcal.kg-1.day-1 lipid IVN. RESULTS: Both IVN regimens resulted in similar changes of nitrogen balance, plasma liver enzymes, blood urea, plasma albumin, and plasma prealbumin. Mean plasma transferrin rose significantly after glucose IVN (p less than 0.01), a change greater than that after lipid IVN (p less than 0.05). Lipid IVN resulted in continued net efflux of alanine from peripheral tissues at rates similar to pretreatment values; glucose IVN significantly reduced net alanine efflux (p less than 0.05). Most of the extra alanine produced by peripheral tissues during lipid IVN appeared to derive from an increased uptake of intramuscular glutamate and from an increased uptake of branched chain amino acids. CONCLUSIONS: The results of this study indicate that 38 kcal.kg-1.day-1 lipid IVN was equivalent to glucose IVN, except for the continuing gluconeogenesis of alanine and the delayed recovery of plasma transferrin concentration after surgery. A greater infusion rate of such a regimen may be necessary to provide sufficient glucose to suppress gluconeogenesis.

Adult↗

PubMed1991

Endotransglycosylation of xyloglucans in plant cell suspension cultures.

1. A xyloglucan-derived nonasaccharide ([3H]XG9; Glc4,Xyl3,Gal,Fuc) was neither taken up by cultured plant cells nor appreciably hydrolysed by them, but a proportion of it became incorporated into extracellular polymers in all cultures tested (Spinacia, Daucus, Rosa, Acer, Capsicum, Zea and Festuca). 2. In Spinacia these polymers were soluble in 20% (w/v) trichloroacetic acid, had apparent Mr 20,000-30,000, were able to bind reversibly to cellulose powder and were susceptible to hydrolysis by endo-beta-(1----4)-D-glucanase, indicating that they were xyloglucans. 3. The linkage formed between [3H]XG9 and the xyloglucan was alkali-stable and glucanase-labile, indicating that the reaction responsible for the incorporation was a transglycosylation. 4. The reducing terminus of the XG9 moiety remained reducing (convertible into [3H]glucitol by NaBH4) after incorporation into the polymer, showing that the XG9 was the glycosyl acceptor and the polysaccharide the donor. 5. The results provide the first evidence that polymeric xyloglucans are subject in vivo to cleavage followed by transfer of the cut end on the other xyloglucan-related molecules. 6. Similar endotransglycosylation reactions could occur within the primary cell wall, between pairs of high-Mr structural xyloglucan molecules. Such a reaction would provide a mechanism for reversible wall loosening and may thus be relevant to our understanding of plant cell growth.

Carbohydrate Conformation↗

PubMed1991

The patient's story: integrating the patient- and physician-centered approaches to interviewing.

Patients produce biopsychosocial stories that integrate material from the medical and personal aspects of their lives. Capturing the personal aspect of the story requires that a patient-centered approach to clinical interviewing complement the equally important physician-centered approach. Patient-centered interviewing actively involves the patient and ensures that his or her perceptions, needs, and concerns are articulated during the physician-patient interaction. In our article, we define patient-centered interviewing and provide a rationale for using it. We also describe how patient-centered interviewing is done, how it is integrated with the physician-centered approach, and how to understand the product of this complementary approach to clinical interviewing, the patient's biopsychosocial story.

Humans↗

PubMed1991

Exocrine pancreatic function and chronic unexplained dyspepsia. A case-control study.

The aim of this study was to determine the prevalence of diminished mean tryptic activity (MTA) in duodenal juice of patients with nonulcer dyspepsia following injection of a Lundh test meal. Two separate studies were undertaken. The first examined a consecutive group of 100 patients with suspected pancreatic disease referred over a period of 2 yr. In these patients, receiver-operating-characteristic analysis was used to determine the point of best discrimination, which occurred at 7 microEq/mL/min when non-pancreatic disease patients were compared with those with chronic pancreatitis or pancreatic cancer. The second study involved 22 patients with endoscopically confirmed nonulcer dyspepsia. The MTA for the patients with unexplained dyspepsia did not differ from 17 healthy controls, but a further 16 pancreatic disease control patients had significantly decreased values (p less than 0.01). Six patients with unexplained dyspepsia (27%) had an MTA of 7 microEq/min/mL or less, indicating impaired pancreatic function, which was more frequent than in healthy controls (p = 0.02). These six patients had significantly different symptoms, being more likely to have pain radiating through to the back (p = 0.017) and pain waking them from sleep (p = 0.002), and less likely to have postprandial pain (p = 0.045). It was of interest that the alcohol intake was not greater in these six patients. It is concluded that pancreatic disease may explain the symptoms of some patients with nonulcer dyspepsia.

Adult↗

PubMed1991

Gender differences in Manning criteria in the irritable bowel syndrome.

The objective of this study was to determine if gender differences exist when using the Manning criteria for diagnosis of irritable bowel syndrome. In an outpatient setting, 61 women and 36 men with entry complaints of abdominal pain, altered bowel habits, or both underwent full evaluation by board-certified/eligible gastroenterologists who also systematically rated the presence or absence of the six Manning criteria. Irritable bowel syndrome was defined as the absence of an organic disease explanation for the entry complaints. This determination was made by two other board-certified gastroenterologists after patients had been in the study for 9 months. These raters were independent of the study and rated the transcripts of patients' clinic visits, all other available clinical data from this and other clinics, all laboratory data obtained during the 9-month study period, and the results of a 9-month telephone follow-up to patients and their physicians. Sixty-five percent of the study population had no organic disease explanation for the entry symptoms, thereby representing irritable bowel syndrome for this study. A similar proportion and type of organic disease and irritable bowel syndrome were experienced by men and women. For the total sample of 97 subjects, the correlation of the Manning criteria with irritable bowel syndrome was 0.22 (P less than 0.01). In the 61 women, correlation between the Manning criteria and irritable bowel syndrome was significant (r = 0.47; P less than 0.01). In the 36 men, however, the correlation was in the opposite direction, although it was not significant (r = -0.16). It was concluded that significant gender differences exist when using the Manning criteria for the diagnosis of irritable bowel syndrome and that the Manning criteria were not of diagnostic value in men.

Colonic Diseases, Functional↗

PubMed1991

Degradation of uric acid during autocatalytic oxidation of oxyhemoglobin induced by sodium nitrite.

The oxidation of oxyhemoglobin produced by sodium nitrite occurs in two stages: 1) an initial slow phase followed by 2) a rapid autocatalytic phase that carries the reaction to completion. The length of the slow phase is extended when uric acid is added to the reaction mixture. As the concentration of uric acid increases, the length of the slow phase increases until a concentration is reached at which the rate of methemoglobin formation is nearly linear until the reaction is complete. Further increases in the concentration of uric acid do not affect the rate of the reaction in the slow phase. At low concentrations of uric acid, where an autocatalytic phase is reached, uric acid is degraded during the reaction. At concentrations of uric acid that keep the reaction in the linear phase, the uric acid is not degraded. It is concluded that uric acid may protect oxyhemoglobin by reacting with HbO2H to yield [HbOH]+ and the urate radical. The urate radical may react with a second molecule of HbO2H and become oxidized. At higher concentrations, the radical may undergo electron transfer with oxyhemoglobin to regenerate the uric acid and form methemoglobin.

Animals↗

PubMed1991

The maternal gene product D7 is not required for early Xenopus development.

The Xenopus D7 gene codes for a novel protein whose expression is restricted to early development. D7 protein is synthesized for the first time during oocyte maturation (1988, Genes Dev. 2, 1296-1306). Injection of D7 RNA into the full-grown oocyte and its subsequent translation into D7 protein neither induced oocyte maturation nor affected the kinetics of hormone-induced maturation. Overexpression of D7 protein by 20-fold in the early Xenopus embryo by injection of D7 RNA into fertilized eggs did not affect subsequent development. Oocytes specifically lacking D7 mRNA were generated by oligodeoxynucleotide-mediated RNA destruction within the oocyte. Unfertilized eggs generated from such oocytes lacked detectable D7 protein, but nevertheless could be activated and fertilized. Embryos generated from such eggs, estimated to contain less than 5% of wildtype levels of D7 protein, developed normally up to the tailbud stage. Thus the D7 protein, the product of a maternal mRNA that is under strict translational repression in oocytes, appears not to be required for oocyte maturation, activation, fertilization or early embryonic development in Xenopus.

Animals↗

PubMed1991

Postoperative myocardial ischemia in patients undergoing coronary artery bypass graft surgery. S.P.I. Research Group.

Cardiac morbidity and mortality after coronary artery bypass graft (CABG) surgery continue to be significant problems. To determine the prevalence, characteristics, and prognostic importance of postoperative myocardial ischemia after CABG surgery, the authors monitored 50 patients continuously for 10 perioperative days with the use of two-lead electrocardiography (ECG). ECG changes consistent with ischemia were defined as a reversible ST depression of 1 mm or greater or an elevation of 2 mm or greater from baseline, lasting at least 1 min. Baseline was adjusted for positional changes and temporal drift. All episodes were verified, with the use of the ECG monitor printout (ECG complexes), by two independent blinded investigators. Clinical care was not controlled by study protocol, and clinicians were unaware of the research data collected. Twenty-six of 50 patients (52%) had 207 episodes of perioperative ischemia (3,409 ischemic minutes). Postoperatively, ischemia developed in 48% of patients, compared with 12% preoperatively and 10% intraoperatively before bypass. Postoperative ischemia was most common in the early period (postoperative days [PODs] 0-2; 38% of patients), peaking during the first 2 h after revascularization, and less common during the late postoperative period (PODs 3-7; 24% of patients). Almost all (120 of 122; 98%) postoperative episodes (after tracheal extubation) were asymptomatic: only 9 of 70 (13%) early episodes were detected by clinical ECG monitoring. Postoperative ischemia did not appear to be related to acute changes in myocardial oxygen demand: only 39% of the postoperative episodes were preceded by a greater than 20% increase in heart rate. However, tachycardia persisted throughout the postoperative week (22-33% of all heart rates greater than 100 beats per min), and patients with postoperative ischemia (POD 0) more frequently had tachycardia (median 43% vs. 12% of the time; P less than 0.01). Five adverse cardiac outcomes occurred on the day of surgery; all five were preceded by postoperative ischemia, three by intraoperative ischemia before bypass, and none by preoperative ischemia. Patients with late postoperative ischemia did not have an adverse cardiac outcome. The authors conclude the following: 1) ischemia is more prevalent postoperatively than preoperatively or intraoperatively before bypass; 2) the incidence of postoperative ischemia peaks shortly after revascularization, during which time it is symptomatically silent, difficult to detect, and related to adverse cardiac outcome; 3) late postoperative ischemia also is silent, but it is less prevalent and not associated with in-hospital adverse cardiac outcome; and 4) a relationship between ischemia and persistently elevated postoperative heart rate may exist and warrants additional investigation.

Adult↗

PubMed1991

Chemical shift artifact: dependence on shape and orientation of the lipid-water interface.

On magnetic resonance images, chemical shift artifact (CSA) can be seen at a planar lipid-water interface oriented within the plane of the phase-encoding and section-select directions (ie, perpendicular to the frequency-encoding direction). Phantoms and a clinical case were used to demonstrate that when a lipid-water interface is curvilinear (eg, spherical) or planar but not oriented along the section-select direction, CSA may be absent or diminished. This effect can be seen at interfaces of normal structures (kidneys, bladder) as well as at interfaces with pathologic lesions such as lipid-containing dermoids. Not only is this effect dependent on section thickness, field of view, matrix size, and receiver bandwidth, but it is also strongly dependent on the orientation of the interface with respect to the section-select direction. Knowledge of the factors that can alter CSA is important since it is used to distinguish lipid-containing from nonlipid-containing structures of similar signal intensities.

Adult↗

PubMed1991

Contamination of operating room personnel during total arthroplasty.

The authors prospectively evaluated the degree of contamination to the operating room team during 60 consecutive total joint arthroplasties. Each member of the team was required to wear a hood, mask, protective eyewear, and shoecovers. At the conclusion of each procedure, all members were assessed in terms of degree and location of contamination. One hundred percent of the surgeons and first assistants were exposed. The face and eyewear were noted to be the area of greatest contamination. The authors found orthopedic surgeons to be at significant risk of contamination with blood and body fluids during total joint arthroplasty.

Blood↗

PubMed1990

2-Imidazolethiones protect ascorbic acid from oxidation induced by copper.

The oxidation of ascorbic acid to dehydroascorbic acid was accelerated by metal ions such as copper. This stimulation of ascorbate oxidation was inhibited by the addition of 2-imidazolethiones and other sulfhydryl-containing compounds, but not by 2-imidazolones or phenytoin. Although the 2-imidazolethiones interacted with copper, as shown by a decrease in the ultraviolet absorbance of the compounds, the product formed still protected ascorbate from oxidation. The 2-imidazolethiones are proposed to complex copper through their free -SH groups.

Ascorbic Acid↗

PubMed1990

Psychosocial factors are associated with health care seeking rather than diagnosis in irritable bowel syndrome.

The objective of this prospective study was to test the hypothesis that 6 reportedly important psychosocial factors were useful criteria for diagnosing the irritable bowel syndrome. Ninety-seven new patients with entry complaints of abdominal pain, altered bowel habits, or both underwent full evaluation by board-certified or -eligible gastroenterologists in an outpatient setting. The independent measures were 6 questionnaires concerning anxiety, depression, stress, lack of social support, somatization, and abnormal illness behavior. The dependent measure, irritable bowel syndrome, was defined as the absence of an organic disease explanation for patients' entry complaints. Two other board-certified gastroenterologists, independent of the study, made this determination. Their rating was based on full review of transcripts of patients' clinic visits, laboratory data, and the results of a 9-mo telephone follow-up to patients and their physicians. Sixty-five percent of the sample had no organic disease explanation for the entry symptoms, thereby representing irritable bowel syndrome. The psychosocial predictors did not show a significant association with irritable bowel syndrome; the power of the study was 0.86. Post hoc analysis revealed that patients with organic disease, as well as patients with irritable bowel syndrome, had significantly more (p less than 0.01) psychosocial abnormality than normal subjects, which likely contributed to the inability of the psychosocial predictors to distinguish irritable bowel syndrome from organic disease. It was concluded that psychosocial criteria were of limited value in differentiating irritable bowel syndrome from organic disease but that they were determinants of health care seeking for the entire study group.

Adult↗

PubMed1990

Synthesis of a 180 kDa protein is a molecular marker of Xenopus oocyte meiotic maturation.

Xenopus oocyte maturation can be induced in vitro by a number of agents including hormones, proto-oncogenes and cyclins. Xenopus oocytes matured by a variety of treatments, including progesterone, insulin, testosterone and injection of Xenopus c-mos RNA, Xenopus cyclin B2 RNA and egg extracts, synthesize a predominant 180 kDa protein (p180). p180 synthesis begins during maturation prior to germinal vesicle breakdown (GVBD) but is prominent only in oocytes that have undergone GVBD. p180 synthesis is thus a useful, reliable molecular marker of oocyte maturation. p180 continues to be synthesized in eggs and embryos up to the gastrula stage of embryogenesis, but not in the neurula or tailbud embryo.

Animals↗

PubMed1990

Quinazoline antifolate thymidylate synthase inhibitors: alkyl, substituted alkyl, and aryl substituents in the C2 position.

Modification of the potent thymidylate synthase (TS) inhibitor N-[4-[N-[(2-amino-3,4-dihydro-4-oxo-6-quinazolinyl)methyl]-N-prop-2- ynylamino]benzoyl]-L-glutamic acid (1a) has led to the synthesis of quinazoline antifolates bearing alkyl, substituted alkyl, and aryl substituents at C2. In general the synthetic route involved the coupling of the appropriate diethyl N-[4-(alkylamino)benzoyl]-L-glutamate with a C2-substituted 6-(bromo-methyl)-3,4-dihydro-4-oxoquinazoline followed by deprotection using mild alkali. Good enzyme inhibition and cytotoxicity were found with compounds containing small nonpolar groups in the C2 position with the 2-desamino-2-methyl analogue 3a being the most potent. Larger C2 substituents were tolerated by the enzyme, but cytotoxicity was reduced. Highly potent series were followed up by the synthesis of a number of analogues in which the N10 substituent was varied. In this manner a number of interesting TS inhibitors have been prepared. Although none of these was more potent than 1a against the isolated enzyme, over half of the compounds prepared were more potent as cytotoxic agents against L1210 cells in culture. The potential of such compounds as useful antitumor agents was further enhanced by the finding that the improved aqueous solubilities of compounds such as 3a over 1a were reflected in vivo in that 3a was at least 5 times less toxic to mice than 1a.

Animals↗

PubMed1990

Refractive changes in silicone filled eyes.

In this study we examined refractive changes of 34 eyes in 34 patients treated with silicone oil injection. Six patients presented with aphakic retinal detachment, another 14 were rendered aphakic after silicone oil injection, one was pseudophakic and 13 were still phakic at the time of writing this report. Silicone oil in the vitreous cavity induced a myopic shift in aphakic eyes and a hypermetropic shift in phakic eyes. This tended to render phakic high myopes and aphakes closer to emmetropia. The resultant refraction was dependent on the shape of the silicone oil bubble inside the eye and influenced by the posture of the patient. In phakic patients the ability to accommodate was markedly reduced.

Accommodation, Ocular↗

PubMed1990

What rate of infusion of intravenous nutrition solution is required to stimulate uptake of amino acids by peripheral tissues in depleted patients?

We examined the effect of varying the quantities (0, 0.1, 0.2, 0.3, and 0.4 gN.kg-1.[day]-1) of nitrogen input on N balance, 3-methylhistidine (3MH) excretion, plasma amino acid concentration and the net flux of amino acids across the leg in depleted patients requiring parenteral nutrition. The calorie-to-nitrogen ratio was 140 to 1 (kcal:1 gN) and consequently the patients received varying amounts of calories (8, 14, 28, 42, and 56 kcal.kg-1.[day]-10. There was negative nitrogen balance and net loss of amino acids from the limb during fasting. An infusion of 0.2 gN.kg-1.[day]-1 of IVN reversed the net catabolic process and resulted in equilibrium of peripheral total amino acid flux and of tyrosine flux without a decrease in 3MH excretion. Net uptake of total amino acids and tyrosine in peripheral tissues was achieved with 0.4 gN.kg-1.[day]-1 and 56 kcal.kg-1.[day]-1. This was associated with a fivefold increase in 3MH excretion (p less than 0.01), indicating that net anabolism occurred with increased protein turnover. Fifty per cent of the amino acids taken up by peripheral tissues during infusions of 0.4 gN.kg-1.[day]-1 was due to the uptake of glutamate (Glu) and 20% was due to the uptake of branched chain amino acids (BCAA). Plasma Glu concentration, [Glu], did not increase with increasing IVN infusion, but BCAA concentrations did. Although the mean plasma [Glu] did not change with IVN infusion, there was an independent effect of plasma [Glu] (p less than 0.0001) and of N input (p less than 0.0001) on Glu flux, indicating that even at high infusion rates the maximal capacity of peripheral tissues to take up Glu had not been reached.

Amino Acids↗

PubMed1990

Inhibition by white light of rb absorption in the root apex of corn.

Measurements of cell lengths made at 0.5 millimeter intervals in median longitudinal sections of the primary roots of corn (Zea mays) were used to construct a growth curve. The region 1.5 to 4.0 millimeters from the apex contained the largest number of elongating cells. Absorption of (86)Rb(+) was measured using intact, dark-grown corn seedlings. Following uptake and exchange, the terminal 8.0 millimeters of each root was cut into four 2.0 millimeter segments. Maximum (86)Rb(+) uptake occurred in the region from 0.0 to 4.0 millimeter from the root tip. Washing the intact primary root in fresh 2.0 millimolar CaSO(4) for 2 hours prior to uptake augmented the rate of (86)Rb(+) uptake in all regions. Illumination with white light during washing caused a reduction of (86)Rb(+) uptake as compared with controls washed in darkness, and the region of greatest light response was the region of elongation. Removal of the coleoptile prior to washing did not prevent the light inhibition of subsequent (86)Rb(+) uptake. Removal of the root cap prior to washing in light partially reversed the light-induced inhibition of the washing response.

Journal Article↗