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Biomedical subjects

D S Smith

Publications and source records attributed to D S Smith.

At least 199 records · Page 11Linked to original sources
PubMed1988

The simultaneous measurements of tissue oxygen concentration and energy state by near-infrared and nuclear magnetic resonance spectroscopy.

The oxygenation and energy states of brain tissues were measured simultaneously by near-infrared photometry and nuclear magnetic resonance spectroscopy in situ. In both cat and dog, the critical hemoglobin oxygenation was 10%, below which the ratio of phosphocreatine (PCr) to inorganic phosphate (Pi) started to fall. The fall of PCr/Pi paralleled the reduction of copper in cytochrome aa3. The separation of the cytochrome aa3 signal from that of hemoglobin by our optical method was confirmed by the substitution of blood by fluorocarbon solution. The energy-oxygen diagram (PCr/Pi against hemoglobin oxygenation, HbO2) was the same in normal- and fluorocarbon substituted cats, but energy curve shifted to the right in the latter when PCr/Pi plotted against the inspired oxygen, FiO2.

Animals↗
PubMed1988

Appearance and partial purification of a high molecular weight protein in crabs exposed to saxitoxin.

This paper provides evidence for a protein component which appears to be involved in the seasonal resistance of small shore crabs, Hemigrapsus oregonesis and Hemigrapsus nudus to saxitoxin, a principle neurotoxin involved in paralytic shellfish poisoning (PSP). This unique protein complex was isolated and partially purified by ion exchange chromatography using DEAE-cellulose from visceral tissue extracts of resistant crabs. The complex was absent in control crabs that were sensitive to saxitoxin. In addition, the protein complex was induced in the crab after acute administration of low doses of saxitoxin. Results indicate that the protein complex is acidic in nature and has an apparent mol. wt of 145,000.

Animals↗
PubMed1988

Pediatric intraosseous infusions: impact on vascular access time.

A 1-year retrospective chart review was performed to evaluate the effect of intraosseous infusions (IO) on the time required to establish vascular access in pediatric patients requiring immediate vascular access for resuscitation. Eighty-one patients were identified, including 29 pulseless and non-breathing and 52 noncardiopulmonary arrest children, who required intravenous fluids or medication for resuscitation. Comparing the results with a previous review, the IO method effectively reduced the time needed to establish vascular access in the arrested group when standard techniques failed, particularly in the child less than 2 years old. The IO method was not used effectively in the non-arrest group, as evidenced by a significantly greater mean time required to establish vascular access. There were no significant complications related to the IO procedure. Nine (50%) of the patients receiving IO fluids or medication had clinical and/or laboratory evidence that these substances reached the central circulation. Early use of IO infusion in the resuscitation is recommended for not only the arrested patient, but also the critical nonarrested patient requiring immediate vascular access.

Bone Marrow↗
PubMed1988

Comparison of time-resolved and -unresolved measurements of deoxyhemoglobin in brain.

Continuous (CW) and pulsed light were used for the noninvasive measurement of hemoglobin oxygenation in tissues. A dual wavelength method of continuous illumination spectroscopy used 760 nm (deoxyhemoglobin peak) and 800 nm (an oxyhemoglobin-deoxyhemoglobin isosbestic point) to measure the kinetics and extent of oxyhemoglobin deoxygenation in brains during mild ischemia/hypoxia. Absorption and scattering were modeled in an artificial milk/yeast blood system, which gave an exponential relationship between absorption and optical path length to a depth of 7 cm. Time-resolved spectroscopy (10-ps resolution) afforded a display of the times and distances of arrival of photons emitted by the cat brain in response to a 10-ps input pulse. The emitted photons rose to a peak in a fraction of a nanosecond and declined exponentially over a few nanoseconds. The half-time of exponential decay corresponds to photon migration over a distance of 4 cm. Exponential light emission continued for several more nanoseconds when the brain was encased by the skull, which plays a key role in prolonging light emission. The exponential decline of light intensity has a value [exp(-microL)], where L is the path length determined from the time/distance scale and mu is the characteristic of the migration of light in the brain. The factor mu is increased by increasing absorption, and mu' = epsilon C where epsilon and C are the Beer-Lambert parameters of extinction coefficient (epsilon) and concentration (C). Thus, deoxyhemoglobin can be quantified in brain tissues.

Animals↗
PubMed1988

The influence of fentanyl upon cerebral high-energy metabolites, lactate, and glucose during severe hypoxia in the rat.

The effects of intravenous administration of high-dose fentanyl (100 micrograms.kg-1, loading dose followed by an infusion of 200 micrograms.kg-1.h-1) were compared with those of a barbiturate (pentobarbital sodium 25 mg.kg-1, intraperitoneal) or hypothermia (rectal temperature 32 degrees C) on changes in cerebral cortical tissue levels of adenosine triphosphate (ATP), phosphocreatine (PCr), lactate, and glucose in severely hypoxemic rats (PaO2 13-23 mmHg for 20 min) with unilateral (left side) carotid ligation (10-12 animals in each group). Ligation of the carotid artery alone produced no change in brain high-energy metabolites, lactate, or glucose. The control values on the ligated side (nitrous oxide, 70%, + normoxia group) for cortical ATP, PCr, lactate, and glucose were 2.86 +/- 0.09 (mumol.g-1 wet weight, mean +/- 1 SE), 3.83 +/- 0.11, 1.68 +/- 0.21, and 3.29 +/- 0.47, respectively. Hypoxia (nitrous oxide, 70%, + hypoxia group) produced a significant (P less than 0.05) decrease in ATP (1.83 +/- 0.37) and PCr (1.93 +/- 0.48) and an increase in lactate (15.8 +/- 1.77) compared with the normoxic group, whereas brain glucose was not significantly changed (1.97 +/- 0.65). Fentanyl (fentanyl + hypoxia group) did not prevent the deleterious effects of hypoxia on cortical high energy metabolites (ATP, 2.0 +/- 0.27; PCr, 2.24 +/- 0.3) or lactate (19.33 +/- 3.16); however, fentanyl caused no alteration in high-energy cerebral metabolite concentrations in normoxic rats, nor did fentanyl produce a significant difference in brain tissue glucose or lactate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1988

Pediatric sexual abuse management in a sample of children's hospitals.

Medical directors of pediatric emergency departments were surveyed by mail to determine the present role of their pediatric hospitals in general, and emergency departments in particular, in the evaluation and management of pediatric sexual assault and abuse. Seventy-four percent of the responses were from communities with an estimated yearly incidence of sexual abuse cases greater than 500. Sixty-eight percent of the communities had a designated pediatric sexual assault center. Thirty-two percent were affiliated with adult facilities and 68% with pediatric facilities. Of those hospitals responding, initial evaluation was most often performed in the emergency department in 77%. Most initial evaluations were performed by resident (PL-2 or above) level physicians (59%). The availability of non-physician professionals, eg, social workers, was felt to be always or usually adequate in 57% and occasionally, rarely, or never adequate in 43%. Estimated physician time required for evaluations averaged less than 60 minutes in 52%, 60 to 90 minutes in 32%, and greater than 90 minutes in 16%. Other patients were felt to be always or frequently compromised in 34% and occasionally compromised in another 44%. The directors rated the abilities of their respective departments to evaluate and manage these patients as excellent in 33%, good in 33%, adequate in 29%, and inadequate in 4%.

Adolescent↗
PubMed1988

Design and development of a single-reagent polarization fluoroimmunoassay for methamphetamine.

The design and development of reagents suitable for use in single-reagent polarization fluoroimmunoassay of methamphetamine is described. The single-reagent method requires that a substantial fraction of antibodies exhibit fast dissociation of bound tracer. Antiserum obtained early in the course of immunization of a sheep with a methamphetamine immunogen had suitable dissociation characteristics. Tracers with bridges of different length between methamphetamine and the fluorescein label group were prepared and evaluated. A single-reagent assay with sensitivity and specificity suitable for urine screening application was demonstrated.

Animals↗
PubMed1988

Development of a direct fluoroimmunoassay for serum levels of 17-hydroxyprogesterone.

A direct, rapid and highly specific fluoroimmunoassay for determining serum levels of 17-hydroxyprogesterone has been developed. It is based on the use of a sheep antiserum covalently coupled to magnetisable particles and fluorescein-labelled steroid. Sodium salicylate is employed to eliminate interference from endogenous binding proteins in serum. The sensitivity of 0.5 nmol/L is adequate for clinical purposes. Analytical recovery, linearity and precision are satisfactory and the results obtained correlate closely with those of an established radioimmuno-assay using 3H-labelled steroid and the same antiserum after initial sample extraction and chromatography. The values found for serum from normal adult subjects ranged from 1.0 to 12.6 nmol/L while those from treated and untreated patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency were 1.5 to 19.0 and 28.0 to 655 nmol/L, respectively.

17-alpha-Hydroxyprogesterone↗
PubMed1988

Professionals earn Master's and maintain careers at same time.

To accommodate professionals who wish to further their education while meeting their career and family responsibilities, the University of Colorado at Denver and the Western Network for Education in Health Administration designed the Executive Program in Health Administration. A major portion of the program instruction is done through computer conferencing and both residential and nonresidential course work, with students attending on-campus classes for 11 weeks over a 25-month period. On completion of the Executive Program, students earn the master's of science and health administration degree. The students are assigned course work and tested by computer, which they use to talk with professors and form study groups with one another.

Colorado↗
PubMed1987

Human antibodies to phosphocholine. IgG anti-PC antibodies express restricted numbers of V and C regions.

We examined the IgG subclass composition and isoelectric focusing (IEF) spectrotype pattern of naturally occurring human IgG antibodies that bind phosphocholine (PC) and found direct evidence for restricted expression of both V and C regions among these antibodies. In most individuals, the isotype of these IgG anti-PC antibodies was primarily IgG2. However, serum from some individuals contained significant amounts of IgG1 and IgG3 anti-PC antibodies. We also found that in individual sera, anti-PC antibodies are pauciclonal, as demonstrated by restricted spectrotypic patterns of the anti-PC antibodies. The IEF pattern of these antibodies were for the most part unique for each individual. In some sera, certain anti-PC antibodies with isoelectric points of basic pH bound PC conjugated to bovine serum albumin (PC-BSA) but did not bind pneumococcal C-carbohydrate bearing PC determinants. In two individuals, we found that the spectrotypes that bound only PC-BSA were of the IgG1 subclass. Taken together, these findings demonstrate that within individual sera, human antibodies to PC are quite restricted in both V and C region expression, and furthermore, these V and C regions of human Ig may not randomly associate.

Autoantibodies↗
PubMed1987

Subclass distribution of human antibodies to Haemophilus influenzae type b capsular polysaccharide.

The polysaccharide (PS) capsule of Haemophilus influenzae type b (Hib) is a "simple" antigen, polyribosylribitolphosphate. Although similar carbohydrate antigens have been reported to elicit IgG antibodies relatively restricted to the IgG2 subclass in man, we report here that Hib PS elicits substantial quantities of both IgG1 and IgG2 serum antibodies in most individuals. Because the determination of IgG subclass distribution can be technically difficult, we used four different approaches to establish our finding. First, we used an IgG subclass-specific, antigen-specific "sandwich assay." Second, we measured IgG subclasses of purified antibodies to Hib PS. Third, we showed that significant amounts of IgG anti-PS can be absorbed with a monoclonal anti-IgG1 affinity column. Fourth, we showed that IgG1 and IgG2 fractions of immune sera have clonally restricted anti-Hib PS antibodies that are easily distinguishable by their isoelectric points. The data indicate that both IgG1 and IgG2 contribute substantially to the IgG antibody response of most adults to immunization with Hib PS.

Adult↗