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D Smith

Publications and source records attributed to D Smith.

At least 505 records · Page 28Linked to original sources
PubMed1996

Selected ion flow tube: a technique for quantitative trace gas analysis of air and breath.

The selected ion flow tube (SIFT) technique for trace gas analysis of air and breath is based on soft chemical ionisation of the trace gases to the exclusion of the major air and breath gases, in fast-flowing inert carrier gas, exploiting the ion-molecule reactions that occur between the trace gases and the pre selected precursor ions (H3O+, NO+ and O2+). The physics and ion chemistry involved in the SIFT technique are described, as are the kinetics of the ion-molecule reactions that are exploited to quantitatively analyse the trace gases. Fast on-line data-acquisition hardware and software have been developed to analyse the mass spectra obtained, from which partial pressures of the trace gases down to about 10 parts per billion can be measured. The time response of the instrument is 20 ms, allowing the profiles of the trace gas concentrations on breath to be obtained during a normal breathing cycle. Pilot results obtained with this SIFT technique include detection and quantification of the most abundant breath trace gases, analysis of cigarette smoke, detection of gases present on smokers' breath and accurate measurement of the partial pressures of NH3, NO and NO2 in air. The simultaneous analysis of several breath trace gases during a single exhalation is clearly demonstrated, and thus different elution times for isoprene and methanol along the respiratory tract are observed. This technique has great potential in many clinical and biological disciplines, and in health and safety monitoring.

Air Ionization↗
PubMed1996

Classifying general medicine readmissions. Are they preventable? Veterans Affairs Cooperative Studies in Health Services Group on Primary Care and Hospital Readmissions.

OBJECTIVES: To describe a new quality assessment method used to classify the preventability of hospitalization in terms of patient, clinician, or system factors. DESIGN: The instrument was developed in two phases. Phase 1 was a prospective comparison of admitting residents' and their attending physicians' classifications of the perceived preventability of consecutive admissions to one Veterans Affairs Medical Center (VAMC) excluding admissions to the intensive care unit (ICU). In phase 2, a panel of 10 physicians rated 811 abstracted records of readmissions from nine VAMCs. SETTING: Nine VAMCs across the United States with varying degrees of university hospital affiliation. PATIENTS: Phase 1, 156 patients admitted to the general medicine service at the Durham VAMC. Phase 2, 514 patients accounting for 811 readmissions within 6 months of a general medicine service discharge at nine VAMCs. MEASUREMENTS AND MAIN RESULTS: Physicians used a checklist to record the reason for hospitalization, the preventability of the hospitalization, and, if preventable, a reason defining preventability, which was classified in terms of system, clinician, and patient factors. In phase 2, two physician panelists assessed preventability for each chart. When two panelists disagreed on the preventability of hospitalization, a third panelist, blind to the original assessments, rated the chart. In phase 1, residents and attending physicians rated 33% and 34% of admissions as preventable (kappa = 0.41), respectively. In phase 2, 277 (34%) of 811 readmissions were deemed preventable. Intraobserver accuracy for the assessment of preventability was 96% (kappa = 0.89). interobserver accuracy was 73% (kappa = 0.43). Hospital system factors accounted for 37% of preventable readmissions, clinician factors for 38%, and patient factors for 21%. The nine hospitals differed markedly in their profile of reasons for preventable readmissions (p = .005). CONCLUSIONS: Using a new method of determining the preventability of hospitalizations, we identified several factors that might avert hospitalizations. Focusing efforts to identify preventable hospitalizations may yield better methods for managing patients' total health care needs; however, the content of those efforts will vary by institution.

Adult↗
PubMed1996

Temporal and spatial characterization of neuronal injury following lateral fluid-percussion brain injury in the rat.

The pattern of neuronal injury following lateral fluid-percussion (FP) brain injury in the rat was systematically characterized at sequential time points to identify selectively vulnerable regions and to determine the temporal contribution of primary and delayed neuropathological events. Male Sprague-Dawley rats (n = 28) were killed 10 min, 2 h, 12 h, 24 h, 4 days, and 7 days following a lateral FP brain injury of moderate severity (2.2 atm), or 24 h after a sham injury. Brain sections were stained and analyzed using Nissl, acid fuchsin, and silver staining methods to identify regions with injured neurons or with visible lesions. Extensive numbers of acid fuchsin or silver-stained neurons were observed as early as 10 min after the FP brain injury in regions extending from the caudate/putamen to the pons. The frequency of injured neurons was greatest in the ipsilateral cortex, hippocampus, and thalamus, and a visible loss of Nissl-stained neurons was observed in these regions beginning at 12 h after the FP brain injury. Acid fuchsin-stained neurons were restricted to the same brain regions for all of the survival periods and gradually decreased in numbers between 24 h and 7 days after injury. These findings suggest that lateral FP brain injury in the rat produces a combination of focal cortical contusion and diffuse subcortical neuronal injury, which is present within minutes of the impact, progresses to a loss of neurons by 12 h, and does not markedly expand into other brain regions with survival periods up to 7 days. Furthermore, the acute onset and rapid evolution of the neuronal injury process may have important implications when considering a window of opportunity for pharmacological intervention.

Animals↗
PubMed1996

Deficits in the endogenous redirection of covert visual attention in chronic schizophrenia.

In patients with schizophrenia, abnormal performance on the antisaccade task suggests that for overt attentional shifts, there is difficulty with the endogenous modes have opposite goals. We examined whether patients with schizophrenia also have difficulty with the endogenous control of exogenous orienting when endogenous and exogenous control of exogenous orienting for covert shifts of attention. Fifteen medicated patients with chronic schizophrenia and 15 matched controls performed two versions of the covert orienting of attention task (COVAT). On one COVAT, targets appeared at the cued location (TAC) on all trials. On the second COVAT, targets appeared at the contralateral location to the cue (TCC) on all trials. Reaction time (RT) for TAC and TCC trials was equal in the control group. However, for the schizophrenia group, RT for TCC trials was significantly slower than RT for TAC trials. This indicates that patients with schizophrenia were unable to inhibit the orienting of attention to peripheral cues even when they knew that targets would never appear at the same location as the cue. These results suggest that patients with chronic schizophrenia have difficulty utilizing the endogenous strategies to inhibit exogenous covert attentional shifts.

Adult↗
PubMed1996

The messenger RNAs for the N-methyl-D-aspartate receptor subunits show region-specific expression of different subunit composition in the human brain.

The expression of the messenger RNAs encoding N-methyl-D-aspartate receptor subunits in neurologically normal post-mortem human brain was studied by in situ hybridization. In the caudate, putamen and nucleus accumbens strong hybridization signals were observed for N-methyl-D-aspartate R1-1 messenger RNA but much weaker signals for N-methyl-D-aspartate R1-3 and N-methyl-D-aspartate R1-4, N-Methyl-D-aspartate R1-2 was not detectable. N-methyl-D-aspartate R2B was the only N-methyl-D-aspartate R2 subunit detected in these nuclei. In the hippocampus the messenger RNAs for both N-methyl-D-aspartate R1-1 and N-methyl-D-aspartate R1-4 were strongly expressed in the dentate gyrus, CA3-CA1 pyramidal cells, subiculum, entorhinal cortex and perirhinal cortex. Much lower expression was seen for N-methyl-D-aspartate R1-2 and N-methyl-D-aspartate R1-3. The messenger RNAs for both N-methyl-D-aspartate R2A and N-methyl-D-aspartate R2B, but not N-methyl-D-aspartate R2C, subunits were expressed in the hippocampus. In the temporal cortex all N-methyl-D-aspartate RI isoforms were expressed (N-methyl-D-aspartate R1-1 and N-methyl-D-aspartate R1-4 being the most abundant) and N-methyl-D-aspartate R2A and N-methyl-D-aspartate R2B but not N-methyl-D-aspartate R2C were also moderately expressed. In the brain stem N-methyl-D-aspartate R1-4 was strongly expressed in various nuclei including the locus coeruleus, nucleus centralis superior and deep pontine nuclei. Only weak expression was seen for N-methyl-D-aspartate RI-1 and N-methyl-D-aspartate R1-3 but not N-methyl-D-aspartate RI-2; of the N-methyl-D-aspartate R2 subunits only N-methyl-D-aspartate R2C was found to be expressed in these nuclei. In the cerebellum all the N-methyl-D-aspartate I isoforms were expressed (mostly N-methyl-D-aspartate R1-4) in the Purkinje layer which also expressed N-methyl-D-aspartate R2A and N-methyl-D-aspartate R2C. In the molecular layer cells were found expressing N-methyl-D-aspartate R1-4 and N-methyl-D-aspartate R2B and cells in the granule layer were found to express N-methyl-D-aspartate R1-1, N-methyl-D-aspartate R1-3 and N-methyl-D-aspartate R1-4 and N-methyl-D-aspartate R2C only. Preliminary studies indicated that the messenger RNA for the N-methyl-D-aspartate R2D subunit was not expressed in the above areas of brain. These results give the first demonstration of the distribution of N-methyl-D-aspartate receptor subunit messenger RNAs in the human brain. The region-specific expression of subunit combinations suggests a heterogeneity of N-methyl-D-aspartate receptors with diverse physiological/pathophysiological roles and provides a rationale for the development of discriminatory N-methyl-D-aspartate receptor antagonists to target selective neuronal populations.

Aged↗
PubMed1996

Assessing medication adherence by pill count and electronic monitoring in the African American Study of Kidney Disease and Hypertension (AASK) Pilot Study.

The Medication Event Monitoring System (MEMS), an electronic monitor which records the date and time of bottle cap openings, and pill counts were used to assess patterns of adherence for the primary antihypertensive drug in the African American Study of Kidney Disease and Hypertension Pilot Study (AASK). Blacks with hypertension and moderately reduced renal function were randomized to one of two levels of blood pressure control and to one of three antihypertensive drug regimens: primary therapy with a calcium channel blocker, an angiotension converting enzyme inhibitor, or a beta-blocker. Of the 94 participants in AASK, 91 had MEMS recordings and pill counts for 313 regularly scheduled monthly follow-up visits. The average length of follow-up was 4.6 months. An acceptable level of adherence by pill count was achieved if 80% to 100% of the prescribed pills were not returned to the clinic. Adherence by MEMS to a once-a-day drug dosing schedule was acceptable if 80% of the time intervals between MEMS openings were within 24 +/- 6 h. Acceptable adherence by pill count was observed at 68% of the follow-up visits; MEMS indicated nonadherence at 47% of those visits. Blood pressure was within goal in 50% of the participants who were adherent by both pill count and MEMS throughout their follow-up visits, and only 14% of the participants who were identified nonadherent by one or both methods. These findings suggest that electronic monitoring is a useful adjunct to pill counts in assessing adherence to antihypertensive drugs. Feedback of electronically collected information on dosing intervals to participants and staff may enhance adherence.

Adolescent↗
PubMed1996

Complications of long-term jejunostomy in children.

The authors reviewed 64 jejunostomies performed in 57 patients. Data were collected regarding complications and performance of the catheters. Patient diagnoses were grouped as follows: cystic fibrosis (25), neurological impairment (14), and miscellaneous other (25). Indications were malnutrition (43), inability to feed (17), and gastroesophageal reflux (4). Complications were compared between these groups. The age range was 7 days to 23 years. There were 251 tube changes over 142 years of cumulative site patency, for an average of 1.8 tube changes per year and an average life of 2.2 +/- 2.4 years per site. The longest duration was 11.7 years. Four tube changes resulted in intraperitoneal insertion (6.2% of changes). The overall complication rate was 37.5%. The major and minor complication rates were 21.9% each. Some patients had more than one complication. Stratification of complications by diagnosis showed that the highest incidence was among the neurologically impaired children (64%), followed by those with cystic fibrosis (32%) and then others (28%). Sixty-four percent of major and 54% of minor complications occurred within the first 6 months. The mortality rate was 4.7%. Infections requiring intravenous antibiotics occurred in 9.4% of the sites, at an average site age of 8.7 +/- 7.7 months. Tube dislodgment requiring surgical replacement occurred in 9.4% of the patients. Our mortality and complication rates compare favorably to those of previously reported series. Surgical jejunostomy is a reliable long-term solution to feeding but is associated with a significant risk of complications, especially in neurologically impaired children. The risk is greatest in the first 6 months after insertion, then decreases as the site "matures."

Adolescent↗
PubMed1996

The effect of low-glycemic carbohydrate on insulin and glucose response in vivo and in vitro in patients with coronary heart disease.

The insulin resistance syndrome has recently been implicated in the etiology of coronary heart disease, with a possible metabolic defect at the level of the adipocyte. We report the effects of a low- versus high-glycemic-index (LGI and HGI, respectively) diet on insulin and glucose response as assessed by oral glucose tolerance test (OGTT) and insulin-stimulated glucose uptake in isolated adipocytes in a group of 32 patients with advanced coronary heart disease. The area under the insulin curve following OGTT was significantly reduced after 4 weeks in the LGI group (P < .03), but not in the HGI group. Insulin-stimulated glucose uptake in isolated adipocytes harvested from a presternal fat biopsy was significantly greater following the LGI diet (P < .05). This study demonstrates that simple short-term dietary measures can improve insulin sensitivity in patients with coronary heart disease.

Adipocytes↗
PubMed1996

Bacterial contamination of autologous bone marrow during processing.

As part of an audit of the processing of autologous bone marrow, we found that marrow was often contaminated with organisms potentially pathogenic to neutropenic recipients. One of 14 marrows studied was found to be contaminated before the processing stage and five others became contaminated during processing. The organisms isolated at these stages were Propionibacterium sp., coagulase-negative staphylococci, Staphylococcus aureus and coryneforms, suggesting that the skin was the likely source of contamination. Five out of the 11 marrows returned to patients were found to be contaminated after thawing. Two of these were marrows previously shown to be contaminated with coagulase-negative staphylococci before freezing, and from these coagulase-negative staphylococci were isolated again, in one case the strains were indistinguishable. New organisms isolated after thawing included Bacillus sp. and Corynebacterium sporogenes suggesting contamination from the environment. No infections attributable to these organisms were demonstrated in any of the patients studied.

Bacterial Infections↗
PubMed1996

p53 protein overexpression and response to biomodulated 5-fluorouracil chemotherapy in patients with advanced colorectal cancer.

Biomodulated 5-flourouracil (5-FU) chemotherapy may limit disease progression in up to 50% of patients with metastatic or unresectable carcinoma of the colorectum. However, treatment is expensive and may be toxic. Thus any predictors of response may be clinically and economically valuable. The p53 gene is mutated in more than 50% of colorectal tumours, usually resulting in p53 overexpression. It may regulate cell cycle progression and cellular response to DNA damage. The principal anticancer activity of 5-FU is due to its ability to induce DNA damage. Fifty-nine patients received bolus intravenous 5-FU/folinic acid over 3 months. Response was assessed by CAT scan (WHO criteria). p53 protein overexpression was determined immunohistochemically from paraffin sections of the original primary tumour and resected metastases. Tumour over expression of p53 protein was associated with a lower rate of response and a higher rate of deterioration both radiologically (P < 0.03) and clinically (P < 0.05, chi 2 test for trend), but did not predict survival from start of treatment. Response was unrelated to age, sex, tumour grade, site of disease or chemotherapy schedule. Tumour p53 protein overexpression alone cannot be used to select advanced colorectal cancer patients for chemotherapy but may be useful in association with other markers of tumour biology.

Adult↗
PubMed1996

Liposomal amikacin for treatment of M. avium infections in clinically relevant experimental settings.

In an effort to optimize rational chemotherapy against M. avium infections in a clinically meaningful context, we tested whether liposome-encapsulated amikacin would effectively reduce the bacterial load in (i) intravenously infected immunodeficient SCID mice, (ii) immunocompetent mice in both early and late stages of intravenous infection, and (iii) immunocompetent mice with pulmonary M. avium infection. Although complete eradication of M. avium was never achieved following intravenous infection, mycobacterial CFUs decreased by 3 to 4 logs in the spleens and livers of mice treated for three weeks with twice-weekly intravenous injections of liposomal amikacin and continued to stay low in the liver, even in the absence of specific immunity. Mice treated in the chronic stage of infection equally benefited from therapy and showed signs of attenuated granulomatous inflammation in the liver. Even moribund mice responded to liposomal amikacin by significantly gaining weight and survived their infected untreated littermates by at least 4 months. In contrast, during pulmonary M. avium infection, treatment with liposome-encapsulated amikacin only resulted in a transient plateau of bacterial proliferation in the lungs, and the infection exacerbated immediately after cessation of therapy.

Amikacin↗
PubMed1996

Comparative vaccination of cattle against Boophilus microplus with recombinant antigen Bm86 alone or in combination with recombinant Bm91.

Cattle were vaccinated either with a single recombinant tick antigen, Bm86 or with a combination of two recombinant antigens, Bm86 and Bm91 from the tick Boophilus microplus. In three experiments, the responses of cattle to subsequent challenge with the tick were assessed. The addition of the Bm91 antigen enhanced the efficacy of the vaccination over that with Bm86 alone to a statistically significant degree. Moreover, co-vaccination with two antigens did not impair the response of cattle to the Bm86 antigen. Finally, responses of individual cattle to the two antigens were independent. All of these results may be relevant to the increase in efficacy expected from a dual antigen vaccine.

Animals↗
PubMed1996

Characterization and mapping of Ds-GUS-T-DNA lines for targeted insertional mutagenesis.

The transposition patterns of the Ds-GUS transposon T-DNA in 23 independent single-copy lines have been characterized and the map positions of 10 of them on three of the five Arabidopsis chromosomes are reported. Using overexpressed Activator (Ac) elements as a transposase source, it was found that the primary determinant of transposition frequency is the insertion site of the Ac-T-DNA. Neither the structure of the transposon T-DNA nor, in most cases, its insertion site have a significant effect on transposition frequency. Both the frequency and timing of transposition are influenced by the parent through which the transposon and transposase T-DNAs are transmitted. Overall, nearly 75% of plants in which excision has occurred bear a reinserted element and very short-range transpositions predominate, underlining the advantage of using mapped transposons for insertional mutagenesis.

Arabidopsis↗
PubMed1996

Accreditation programs for hospitals: funding and operation.

Accreditation is a formal process by which an authorized body assesses and recognizes an individual, an organization (like a hospital), a program, or a group as complying with requirements such as standards or criteria. This article analyses and compares the activity and funding of six health care accrediting bodies which operate in five different countries, and which in 1994, accredited over 5000 health centres. The data included in this article could be useful for other institutions who wish to commence accreditation programmes for health care organizations.

Accreditation↗
PubMed1996

Postmortem diffusion of drugs from gastric residue: an experimental study.

Postmortem drug diffusion from gastric residue was assessed in a human cadaver model. Fifty milligrams of amitriptyline (Ami) and 5 g of paracetamol (Par) suspended in 350 ml of 10% methanol, 0.1 N HCl, and 50 ml urograffin with 5 g lithium carbonate (alkaline model) or without lithium (acidic model) was instilled into the stomach through an esophageal tube via a neck dissection. Multiple samples were obtained after 48 h at room temperature (range in mean hourly room temperature: 15.6-20.7 degrees C, n = 9). The pH of the gastric contents (alkaline model range = 8.3-8.9, n = 5; acidic model range = 3.4-3.8, n = 5) had no significant effect. Drug diffusion was most marked in the left lung base, with drug concentrations (micrograms/g) of 0.1-13.9 for Ami, 65-524 for Par, and 13-161 for lithium. Similarly affected were the left lobe of the liver (Ami, 0.1-54.9; Par, 7-218; lithium, 7-39), the spleen (Ami, 0.6-24.3; Par, 104-663; lithium, 27-106), and pericardial fluid (Ami, 0-4.5; Par, 48-641; lithium, 12-56). Diffusion into gallbladder bile, cardiac blood, aortic blood, and blood of the inferior vena cava was less severe. The left kidney and left lung were more severely affected than the right kidney and lung, and similarly the left and right psoas muscles. Least affected was the right anterior lobe of the liver and the lung apexes. This phenomenon may significantly influence drug concentrations in liver and in blood samples obtained from the torso, and consequently liver/blood drug ratios. To circumvent the problem of postmortem drug diffusion from the stomach, it is recommended that blood be sampled from a peripheral vessel, skeletal muscle from a limb, liver from deep within the right lobe, and lung from the apex rather than the base.

Acetaminophen↗