Biomedical subjects

L A Hughes

Publications and source records attributed to L A Hughes.

At least 19 recordsLinked to original sources

PubMed1998

Effect of skin pigmentation on pulse oximetry accuracy in the emergency department.

OBJECTIVE: To determine whether pulse oximeter (PO) accuracy and signal quality are affected by level of skin pigmentation. METHODS: Observational study in a community hospital ED. Consecutive adult patients undergoing arterial blood gas determination were enrolled into the study. Skin pigmentation was determined by comparison with standardized color swatches under controlled lighting; assigned values were used to stratify patients into 3 groups (light, intermediate, and dark) using predetermined criteria. Simultaneous with arterial blood sampling, staff recorded PO reading of O2 saturation using the Nellcor D-25 oximeter. PO values were compared with criterion standard values measured using a 4-wavelength spectrophotometer or co-oximeter. PO signal quality also was recorded. Bias (the mean difference between PO and co-oximeter-measured values of hemoglobin saturation) and precision (the standard deviation of the bias) were calculated. Groups were compared using one-way ANOVA, Bartlett's test for variances, and chi2 test. RESULTS: O2 saturation data were obtained for 284 patients. Bias values did not differ between the 3 skin pigment groups (p = 0.79). Precision was of borderline significance (p = 0.05), but there was no dose-response relation between skin pigmentation and precision. Study personnel reported suboptimal PO function most often among patients in the dark group (p = 0.003), but this finding was of no clinical significance. PO signal failure was rare (<1% of all patients). CONCLUSIONS: Although several prior studies suggest the contrary, this study found that skin pigmentation does not affect the bias or precision of pulse oximetry. Furthermore, skin pigmentation has no clinically significant effect on PO signal quality.

Adult↗

PubMed1997

Alterations in the reproductive patterns of female mice exposed to xenobiotics.

Chemicals, by virtue of their varied interactions with biological molecules, are expected to differ in the way they may alter female reproduction. Reproductive toxicity may reflect effects either on the female germ cells or on various maternal processes such as ovulation, implantation, pregnancy, and parturition. In either case, the ultimate manifestation of chemical toxicity on female reproduction is a decrease in the number of normal young born. Very little information is available on the effects of chemicals that are nonhormonal in nature on the long-term ability of treated females to produce offspring. This report presents the results of long-term female total reproductive capacity (TRC) tests on 29 chemicals, including pharmaceuticals, pesticides, and alkylating and industrial agents. For each chemical, the minimum test involved an evaluation of the maximum tolerated dose administered as a single intraperitoneal injection. Females were single-pair mated with an untreated male for most of the female's reproductive life span (a minimum of 347 days posttreatment) and scored for the number of live births produced during this period. Confirmatory dominant lethal experiments or histological examinations for numbers of small follicles were carried out when mutagenic effects or cytotoxicity, respectively, were suspected as the basis for reduced fertility. Of the 29 chemicals studied, 17 had reproductive effects which may be grouped into one of three classes: (1) those that reduced the total number of young and litters per female, (2) those that reduced the total number of young but not of litters, and (3) those that had no significant effect on the total number of young produced but reduced the size of the first and/or second litters. The TRC provides a capacity for detecting a range of toxic insults upon female reproduction. Many of the chemicals were indeed shown to affect the reproductive performance of females through mutagenic and/or cytotoxic effects on follicles. In some cases, however, no causative mechanism could be identified for the observed reduction in reproductive performance. Nevertheless, with this report the number of chemicals tested by this TRC procedure has been quadrupled and the categories of chemicals tested have been substantially broadened.

Alkylating Agents↗

PubMed1997

A continuum of care model.

An interdisciplinary documentation tool provides a composite of all of the planning activities that occur relative to each individual patient and his/her family before discharge. In response to the Joint Commission on Accreditation of Healthcare Organization's mandate, this tool evolved into a "Continuum of Care" model. Now, all disciplines maintain a patient's continuity of care.

Continuity of Patient Care↗

PubMed1997

Safety of MR imaging in patients who have retained metallic materials after cardiac surgery.

OBJECTIVE: Epicardial pacing wires retained in patients who undergo cardiac surgery are thought to be a relative contraindication to MR imaging. However, to our knowledge no published evidence supports this belief. Because other metallic materials retained after cardiac surgery might represent a hazard to patients who undergo MR imaging, we sought to determine the safety of such imaging. SUBJECTS AND METHODS: We examined 200 patients who underwent MR imaging at 1 or 1.5 T after cardiac surgery. Eighty-one were examined with ECG monitoring. The presence of temporary epicardial pacing wires, prosthetic valves, and other metal materials was confirmed by chest radiography. RESULTS: Of the 200 patients reviewed, all had postoperative metallic material visible on chest radiographs. Temporary epicardial pacing wire, cut short at the skin, was seen in 51 patients. Of the 81 patients examined with ECG monitoring, we found that MR imaging produced no changes from baseline ECG rhythms. None of the 200 patients reported symptoms suggesting arrhythmia or other cardiac dysfunction during MR imaging. CONCLUSION: MR imaging can be performed safely in patients who have undergone cardiac surgery and have retained metallic material, including valve replacements and temporary epicardial pacing wires cut short at the skin. MR imaging of patients with pacemakers was not evaluated, and we recommend that pacemakers remain a contraindication to MR imaging.

Cardiac Surgical Procedures↗

PubMed1996

Dominant lethal mutations, heritable translocations, and unscheduled DNA synthesis induced in male mouse germ cells by glycidamide, a metabolite of acrylamide.

The hypothesis that acrylamide induces dominant lethal mutations and heritable translocations in male mice, not through direct adduction, but by conversion to the reactive epoxide, glycidamide, was investigated. Three studies, namely, induction of dominant lethal mutations, heritable translocations, and unscheduled DNA synthesis in spermatids, which were conducted earlier in this laboratory for acrylamide, were also performed for glycidamide to determine its mutagenic properties and to compare responses. Results of these studies are consistent with the proposal that in vivo conversion to glycidamide is responsible for the mutagenicity of acrylamide in male mice.

Animals↗

PubMed1996

Magnetic resonance imaging of pericardial constriction: comparison of cine MR angiography and spin-echo techniques.

AIM: Spin-echo (SE) MRI detects pericardial thickening in pericardial constriction but the validity of extrapolating SE criteria to cine MRA imaging has not been tested. Pericardial thickness measured by SE and cine MRA was compared in patients with and without pericardial thickening to determine if the range of pericardial thickness measured by the two techniques is the same. PATIENT AND METHODS: Fourteen patients, investigated for possible pericardial constriction (PC), were compared with 24 subjects without evidence of pericardial disease (controls). Images were acquired using SE and cine MRA. Pericardial thickness was compared with final diagnosis. RESULTS: Pericardial thickening ( > 3.5 mm) by SE detected pericardial constriction: sensitivity = 100% specificity = 96%, kappa = 0.91. Cine MRA had a sensitivity = 86%, specificity = 63%, kappa = 0.33. Maximum differences between SE and cine MRA pericardial thickness ranged from +2.5 mm to -2/7 mm. CONCLUSIONS: Spin-echo identifies pericardial thickening with little overlap between measurements in patients with and without pericardial constriction. Pericardial thickness on cine MRA usually exceeds SE thickness, but with considerable overlap of thickness measurements in patients with and without pericardial constriction. Cine MRA cannot be used alone to diagnose pericardial thickening.

Diagnosis, Differential↗

PubMed1996

Time-of-flight MR angiography of the portal venous system: value compared with other imaging procedures.

OBJECTIVE: The purpose of this study was to retrospectively compare two-dimensional time-of-flight MR angiography with other imaging procedures in the evaluation of the portal venous system in 152 consecutive patients. MATERIALS AND METHODS: The findings on MR angiography performed on 152 patients to depict breath-hold, two-dimensional time of flight MR angiography. Selective arterial presaturation, bolus tracking, and three-dimensional reconstruction were used routinely. Findings were correlated with findings on sonography (104 patients), CT (8 patients), and conventional digital subtraction angiography (19 patients) as well as surgery (23 patients). RESULTS: Agreement between results of MR angiography and alternative types of imaging was excellent (99%). Agreement with sonography (100 of 104), CT (8 of 8), conventional angiography (18 of 19), and surgery (23 of 23) was good. Visualization of varices and spontaneous shunts by MR angiography was superior to that by other imaging techniques. CONCLUSION: Our experience shows that time-of-flight MR angiography is reliable and accurate for depicting portal venous anatomy. MR angiography shows vessels that are not visible with sonography. Complicated pathology is clearly visualized in a way that is not possible with other techniques.

Angiography, Digital Subtraction↗

PubMed1995

Comprehension of discharge instructions by patients in an urban emergency department.

STUDY OBJECTIVE: To assess patients' comprehension of their emergency department discharge instructions and to determine if inner-city patients' literacy levels are adequate to comprehend written discharge instructions. DESIGN: Prospective, observational study. SETTING: The ED of an inner-city university hospital. PARTICIPANTS: Two hundred seventeen patients consecutively discharged from the ED during 12 separate time slots. INTERVENTIONS: Patients were interviewed after discharge from the ED and asked to state their diagnosis, medication instructions, and follow-up instructions. Comparisons between patient recall and instructions as written in the chart were assessed by independent raters and scored from poor to excellent. Patients were administered a standardized test of reading ability. RESULTS: Overall comprehension rates were judged to be good, although 23% of patients exhibited no understanding of at least one component of their discharge instructions. Mean reading ability of the patients was at the sixth-grade level. The ED's printed discharge instructions were written at an 11th-grade reading level. Patients with low literacy scores were more likely to have poor comprehension of instructions. CONCLUSION: Overall comprehension rates in this population were good despite the fact that ED instruction sheets were written at an inappropriately high reading level. Verbal instructions given by the discharging physician likely have a significant effect on patients' comprehension of instructions.

Adult↗

PubMed1995

Normal arborization of the deep branch of the ulnar nerve into the interossei and lumbricals.

Ten adult hands were dissected to reexamine in new detail the distribution of the deep branch of the ulnar nerve from its origin in the ulnar tunnel to its termination in the first dorsal interosseous muscle. The relationships of the subdividing branches to each other and to the muscle bellies were clarified. The palmar interossei along with the first and second dorsal interossei were all innervated within the middle third of their corresponding metacarpal. The third and fourth dorsal interossei were innervated within the proximal third of their corresponding metacarpals, and the third lumbrical was innervated within the middle third whereas the fourth lumbrical was innervated along its distal third.

Anthropometry↗

PubMed1995

Studies on the expression of intestinal lactase in different individuals.

Sixty one duodenal biopsy specimens were examined for the expression of lactase at the level of enzyme activity, protein, and messenger RNA. Of the 51 samples with normal villous architecture, 39 were lactase persistent, 11 were nonpersistent (adult type hypolactasia), and one was of indeterminate status. All the lactase persistent individuals showed high mRNA and a high level of the lactase protein as detected by sodium dodecyl sulphate polyacrylamide gel electrophoresis. All the 11 non-persistent individuals tested showed a low level of lactase protein. Nine of the 10 samples tested showed low mRNA and one high mRNA. These results suggest that the lactase persistence polymorphism is controlled at the level of the expression of the lactase gene, though there may be some heterogeneity of the lactase non-persistence phenotype.

Adult↗

PubMed1995

Body magnetic resonance angiography and its effect on the use of alternative imaging--experience in 1026 patients.

Time-of-flight magnetic resonance (MR) angiography has been described for numerous applications but the number of patients described in published reports is usually relatively small. There is little information concerning the general utility of MR angiography in the body, outside the cranial circulation, or its effect on use of other imaging studies. Utilization of two-dimensional (2D) time-of-flight MR angiography over a 3 year period was reviewed to determine its accuracy and impact on other imaging modalities. Cranial and cardiac studies were excluded. Correlation was made with alternative imaging and surgical findings. Between January 1990 and December 1992 2D time-of-flight MR angiography was used to examine 1026 patients. MR angiography was used most frequently to examine the venous system. There was a slight reduction in the use of alternative imaging with two exceptions. When chest MR venography was performed, alternative imaging was completely abolished. Also, contrast portal venography was virtually eliminated. Five errors (0.2% of total MR angiography examinations) were recorded. Time-of-flight MR angiography, especially MR venography, is accurate and can replace contrast venography for abdominal and thoracic applications. Cost and limited availability means that other imaging, usually ultrasound, often precedes MR angiography.

False Negative Reactions↗

PubMed1995

Magnetic resonance angiography of the central chest veins. A new gold standard?

PURPOSE: The systemic chest veins may be difficult to show comprehensively by contrast venography, especially if there is limited venous access or contraindications to intravenous contrast. As an alternative, can magnetic resonance angiography (MRA) reliably detect occluded chest veins and predict suitable sites for central venous access? PATIENTS AND METHODS: Eighty-four patients were examined using breath-hold time-of-flight MRA and three-dimensional image reconstruction. Thirty-three were evaluated to identify possible central venous access. Fifty-seven patients were examined to diagnose and stage central venous occlusion. RESULTS: The associated diagnoses were malignancy 46, parenteral nutrition 21, hemodialysis 6, chemotherapy 4, and other long-term venous access 7. Of the 28 patients in whom MRA predicted a patent site for central venous access, satisfactory access was achieved. In two patients, cannulation of veins shown to be occluded on MRA was attempted unsuccessfully. Correlation with contrast venography was available in 17. There was agreement with MRA concerning the level of occluded veins in all cases. Contrast venography did not show all patent veins, including some accessed during surgical line placement. CONCLUSION: Compared with surgical line placement or contrast venography, MRA of the systemic chest veins is accurate. Patent and occluded chest veins are reliably defined, including potential sites for central line placement, in a way that is not possible with other techniques. MRA may be the new "gold standard" for defining systemic venous anatomy in the chest.

Adult↗

PubMed1994

Limb and lower-body duplications induced by retinoic acid in mice.

The zygote and subsequent preimplantation stages of early mammalian development are susceptible to certain chemical perturbations that cause abnormal development of the conceptus. In certain cases, disruption in patterns of gene expression could be a primary event leading to abnormal development. To investigate this hypothesis, we treated pregnant mice with trans-retinoic acid, a known modulator of gene expression. Treatments were administered at various times during pregastrulation stages and the presumed onset of gastrulation. trans-Retinoic acid induced a distinctive set of malformations, as manifest by supernumerary and ectopic limbs and duplication of portions of the lower body, but only when administered during the period of 4.5-5.5 days after mating. (Other malformations were induced at different stages.) The limb and lower-body duplications suggest that exogenous trans-retinoic acid may influence not only the pattern for the hindlimbs but also that for the entire lower body. Since it appears likely that the embryos were affected in the late blastocyst and proamniotic-embryo stages, the provocative possibility arises that aspects of pattern formation of limbs and lower body actually occur prior to gastrulation.

Animals↗

PubMed1994

Mosaic regulation of lactase in human adult-type hypolactasia.

BACKGROUND/AIMS: We have previously shown that in the proximal-jejunum of hypolactasic humans, just a few villus enterocytes express lactase protein and activity. In the present study, we compared the distribution of lactase messenger RNA (mRNA), protein, and activity in villus enterocytes in tissues obtained from subjects with persistent high lactase activity and those with hypolactasia. METHODS: Immunohistochemical and enzymohistochemical staining was performed on closely adjacent sections of human proximal jejunum from 5 individuals with persistent high lactase activity and 32 with hypolactasia. In all the persistent and in 9 hypolactasic samples, in situ hybridization was also performed using a digoxygenin-labeled RNA probe. RESULTS: In persistent tissues, lactase mRNA, protein, and activity were present in all villus enterocytes. In hypolactasic tissues, lactase mRNA was detected only in some villus enterocytes; some of them also expressed protein and activity, whereas others did not. In 8 of these hypolactasic samples, a variable number of villus enterocytes with lactase mRNA and protein did not express lactase activity. CONCLUSIONS: Various types of enterocytes are present even on a single villus from individuals with adult-type hypolactasia. These results show that different mechanisms control lactase expression in enterocytes on the same villus.

Adult↗

PubMed1994

MR angiography as the sole method in evaluating abdominal aortic aneurysms: correlation with conventional techniques and surgery.

PURPOSE: To compare magnetic resonance (MR) angiography with conventional preoperative imaging techniques and surgical findings in the evaluation of abdominal aortic aneurysms (AAAs). MATERIALS AND METHODS: MR angiography was performed in 40 patients with an AAA. Two-dimensional time-of-flight MR angiography with maximum intensity projections was compared with conventional angiography, ultrasound, computed tomography, and surgery. RESULTS: In 18 of 20 patients, MR angiography demonstrated more extensive disease than did angiography. MR angiography depicted 41 of 43 renal arteries and seven of eight renal artery stenoses (one false-negative finding of mild stenosis) identified at angiography. When iliac arteries were imaged (30 patients), good correlation with angiography was seen in all but one patient (resulting from surgical clip artifact). Ten iliac stenoses were seen at both studies. Angiography caused underestimation of the extent of seven iliac aneurysms. CONCLUSION: MR angiography can provide all of the necessary preoperative information for evaluation of AAA and can replace conventional angiography in many cases.

Aged↗

PubMed1994

Atypical cleft of the palate: a report.

Our early experience with a rare atypical cleft of the soft palate in a 15-month-old female infant is presented. The cleft extended obliquely across the soft palate from the retromolar region on the left to the base of an intact uvula. Surgical management included a three-layer closure and lengthening of the left side of the soft palate. Close follow-up and reporting of the patient's progress are planned.

Cleft Palate↗

PubMed1994

The impact of intraoperative ultrasonography on surgery for liver neoplasms.

To analyze the effect of IOUS on surgical decision making, we performed a retrospective study of 45 patients who had exploratory laparotomy and IOUS for liver neoplasms. Preoperative lesion detection was compared with intraoperative findings. The effect of IOUS on the choice of surgical procedure was analyzed. Preoperative imaging detected 67% of lesions, 78% when combined with surgical inspection and palpation, and 97% were recognized by IOUS. Surgery was modified in 23 of 45 cases (51%); 19 of those 23 cases (83%) were based on IOUS findings alone. IOUS demonstrated superior lesion detection over noninvasive preoperative liver imaging, and IOUS significantly affected surgical decision making.

Adult↗

PubMed1993

Regulation of cytokine mRNA expression in lipopolysaccharide-stimulated human macrophages.

One of the responses of the human macrophage to lipopolysaccharide (LPS) is the production of a number of cytokines. The regulation of these cytokines is still not clearly understood. To study this regulation, mRNA levels of interleukin 1 alpha (IL-1 alpha), IL-1 beta, tumor necrosis factor alpha (TNF-alpha), IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-8/neutrophil chemotactic factor were determined in 10-day-old differentiated macrophages following stimulation with a low dose of LPS (0.001 to 10 ng/mL) with use of the polymerase chain reaction. Increased levels of mRNA for IL-8 were detectable after exposure to a very low dose of LPS (0.001 ng/mL) and levels of IL-1 beta and TNF-alpha were detectable only after stimulation with doses of 0.01 ng/mL. The mRNA for IL-8 was detected 30 minutes after the addition of LPS, while those for IL-1 beta and TNF-alpha were only measurable at 1 hour. The mRNAs for IL-1 alpha, IL-6, and GM-CSF were detectable only with a higher dose of lipopolysaccharide and only after a longer exposure time. In addition, the messages for IL-6 and GM-CSF were measurable for a short time, while those of IL-8 and of IL-1 beta were detectable for a longer time. The secretion of TNF-alpha and GM-CSF tightly followed gene activation, and that of IL-6 and IL-8 steadily increased even after the mRNA level of these cytokines returned to baseline. Secretion of IL-1 alpha and IL-1 beta was hardly detected, although their gene activation was obvious. These data indicate that cytokine mRNA levels following lipopolysaccharide stimulation are highly regulated. Individual cytokines show variable patterns of response. These responses are both dose and time dependent and are not necessarily associated with the secretion of protein.

Adult↗