Biomedical subjects

J D Davis

Publications and source records attributed to J D Davis.

At least 37 records · Page 2Linked to original sources

PubMed1999

Increase in intake with sham feeding experience is concentration dependent.

Most sham feeding studies show that about three sham feeding tests are required for intake to reach maximum. One study, however, using a dilute solution, reported maximum sham intake in the first sham feeding test, suggesting that the progressive rise in sham intake may be concentration dependent. We tested this hypothesis with six groups of rats given five sham feeding tests each with one of six concentrations of sweetened condensed milk (0.5:1, 1:1, 2:1, 4:1, 8:1, 16:1, water-to-milk dilutions). It took three sham tests for intake to reach maximum with the three most concentrated solutions, but only one with the three weakest. Thus the intake of concentrated solutions of milk is limited by two negative feedback signals, one derived from the accumulation of fluid in the gastrointestinal tract, the other from a labile signal that loses its effectiveness with sham feeding experience. In contrast, the intake of weak concentrations is limited only by the nonlabile negative feedback signal because the labile signal is missing.

Animals↗

PubMed1998

Squalamine inhibits angiogenesis and solid tumor growth in vivo and perturbs embryonic vasculature.

The novel aminosterol, squalamine, inhibits angiogenesis and tumor growth in multiple animal models. This effect is mediated, at least in part, by blocking mitogen-induced proliferation and migration of endothelial cells, thus preventing neovascularization of the tumor. Squalamine has no observable effect on unstimulated endothelial cells, is not directly cytotoxic to tumor cells, does not alter mitogen production by tumor cells, and has no obvious effects on the growth of newborn vertebrates. Squalamine was also found to have remarkable effects on the primitive vascular bed of the chick chorioallantoic membrane, which has striking similarities to tumor capillaries. Squalamine may thus be well suited for treatment of tumors and other diseases characterized by neovascularization in humans.

Animals↗

PubMed1998

Health symptoms reported by Persian Gulf War veterans two years after return.

The role of actual or perceived events has considerable importance for individual well-being. Although the Persian Gulf War (PGW) has raised questions about the presence of hazardous environmental exposures, few, if any confirmed exposure data are available. Yet, a substantial number of PGW veterans report health problems since their return from that war. The present study was conducted to investigate possible associations between opportunities for exposure and increased rates of health symptom reporting. First, we examined descriptive data on types and rates of health symptoms reported by a cohort of Gulf War veterans. Then, using proxies for three wartime experiences, we examined associations between health symptoms reports and different Persian Gulf exposure scenarios (reported exposure to poison gas or germ warfare, being in a transportation unit, or high levels of combat exposure), adjusting for the effects of background characteristics (e.g., gender, psychological distress). Findings suggest that reported exposure to poison gas or germ warfare is related to higher symptom reporting by this cohort of New England area veterans. Limitations in the study design and the challenges involved in studying PGW veterans' illnesses are discussed.

Adult↗

PubMed1998

A comparison of ligase chain reaction to polymerase chain reaction in the detection of Chlamydia trachomatis endocervical infections.

OBJECTIVE: To compare the reliability of ligase chain reaction (LCR) to polymerase chain reaction (PCR) in detecting Chlamydia trachomatis endocervical infections. METHODS: We conducted a prospective study of 486 patients at risk for chlamydial infection of the endocervix. We obtained two endocervical specimens from each patient and used LCR and PCR to detect C. trachomatis. Discrepant results between the two techniques were resolved by repeat testing and by testing for the major outer membrane protein (MOMP) gene, if necessary. We determined the sensitivity, specificity, positive predictive value, and negative predictive value for each test, using concordant results or MOMP gene results as the "gold standard". RESULTS: Of the 486 patients, 42 (8.6%) had evidence of C. trachomatis infection after resolution of discrepant results. Of the 42 true positive specimens, 41 were positive by initial LCR and 38 were positive by initial PCR. Of the 444 true negative specimens, none had a positive initial LCR result, while 2 had a positive initial PCR test. Therefore, compared to the gold standard, LCR had a sensitivity of 97.6% and specificity of 100%, while PCR had a sensitivity of 90% and a specificity of 99.5%. The positive and negative predictive values of LCR were 100% and 99.8%, respectively. PCR had a positive predictive value of 95% and a negative predictive value of 99.1%. The difference in sensitivity of LCR versus PCR was not statistically significant (P = .125). CONCLUSION: LCR and PCR perform equally well in detecting C. trachomatis endocervical infections.

Chlamydia Infections↗

PubMed1998

Closing the pylorus decreases the size of large meals in the rat.

We previously reported (Davis, J. D.; Smith G. P.; Sayler, J. L. Reduction of intake in the rat due to gastric filling. Am. J. Physiol. 272:R1599-R1605, 1997.) that confining ingested fluid to the stomach by closing the pylorus decreased the intake of solutions that stimulated particularly large intakes. Those solutions differed in the type of orosensory and postoral stimulation so the nature of the control over ingestion was unclear. We report here a study of the role of orosensory stimulation alone in controlling intake in rats with a closed pylorus. Rats were given 30-min intake tests with the pylorus open and closed with 0.2 M glucose, and with 0.2 M glucose + 1.25 mM sodium saccharin, 2.5 mM sodium saccharin and 5.0 mM sodium saccharin. Intake was reduced on the cuff-closed test relative to the cuff-open test with the two highest concentrations of saccharin, but not with the two lowest. When ingesting the glucose solutions with the two highest concentrations of saccharin the initial rate of ingestion was greater and the decline in the rate of ingestion was slower than when the rats ingested the glucose solutions with 1.25 mM saccharin or no saccharin. We showed by means of a meta-analysis of previously published and unpublished data that a high rate of licking at the beginning of a test combined with a relatively slow rate of decline in the rate of licking during it are the characteristics of ingestive behavior on cuff-open tests that will lead to a reduction of intake when ingested fluid is confined to the stomach.

Animals↗

PubMed1998

Health status of Persian Gulf War veterans: self-reported symptoms, environmental exposures and the effect of stress.

BACKGROUND: Most US troops returned home from the Persian Gulf War (PGW) by Spring 1991 and many began reporting increased health symptoms and medical problems soon after. This investigation examines the relationships between several Gulf-service environmental exposures and health symptom reporting, and the role of traumatic psychological stress on the exposure-health symptom relationships. METHODS: Stratified, random samples of two cohorts of PGW veterans, from the New England area (n = 220) and from the New Orleans area (n = 71), were selected from larger cohorts being followed longitudinally since arrival home from the Gulf. A group of PGW-era veterans deployed to Germany (n = 50) served as a comparison group. The study protocol included questionnaires, a neuropsychological test battery, an environmental interview, and psychological diagnostic interviews. This report focuses on self-reported health symptoms and exposures of participants who completed a 52-item health symptom checklist and a checklist of environmental exposures. RESULTS: The prevalence of reported symptoms was greater in both Persian Gulf-deployed cohorts compared to the Germany cohort. Analyses of the body-system symptom scores (BSS), weighted to account for sampling design, and adjusted by age, sex, and education, indicated that Persian Gulf-deployed veterans were more likely to report neurological, pulmonary, gastrointestinal, cardiac, dermatological, musculoskeletal, psychological and neuropsychological system symptoms than Germany veterans. Using a priori hypotheses about the toxicant effects of exposure to specific toxicants, the relationships between self-reported exposures and body-system symptom groupings were examined through multiple regression analyses, controlling for war-zone exposure and post-traumatic stress disorder (PTSD). Self-reported exposures to pesticides, debris from Scuds, chemical and biological warfare (CBW) agents, and smoke from tent heaters each were significantly related to increased reporting of specific predicted BSS groupings. CONCLUSIONS: Veterans deployed to the Persian Gulf have higher self-reported prevalence of health symptoms compared to PGW veterans who were deployed only as far as Germany. Several Gulf-service environmental exposures are associated with increased health symptom reporting involving predicted body-systems, after adjusting for war-zone stressor exposures and PTSD.

Adult↗

PubMed1998

Pneumoperitoneum as a risk factor for endobronchial intubation during laparoscopic gynecologic surgery.

UNLABELLED: Patients undergoing gynecological surgery under laparoscopic guidance usually receive general anesthesia with endotracheal intubation and mechanical ventilation. The creation of a pneumoperitoneum and the Trendelenburg position, both of which are used to improve visualization, are associated with cephalad movement of the diaphragm. This may increase the risk of endobronchial intubation. We studied the change in the distance from the tip of the endotracheal tube (ETT) to the carina with a fiberoptic bronchoscope in 30 patients aged 21-40 yr who were undergoing laparoscopic tubal ligation (n = 28) or hysterectomy (n = 2). Measurements were taken in the supine and Trendelenburg positions before and after pneumoperitoneum. The average distance from the ETT to the carina in the supine position was 2.1 +/- 0.8 cm and in the Trendelenburg position was 1.8 +/- 0.8 cm (P = not significant). After insufflation of the abdominal cavity, the mean distance decreased to 0.7 +/- 1.4 cm in the supine position (P < 0.05) and was associated with endobronchial intubation in eight patients. The addition of the Trendelenburg position to an established pneumoperitoneum resulted in minimal displacement (0.54 +/- 1.4 cm, P < 0.05) and one additional endobronchial intubation. We conclude that the insufflation of gas in the abdominal cavity, and not the change in patient position, is the main risk factor for endobronchial intubation in patients undergoing laparoscopic gynecologic surgery. IMPLICATIONS: This study demonstrated that in anesthetized women, the insufflation of gas into the abdomen during laparoscopy for gynecologic surgery is the main risk factor for migration of the endotracheal tube into a bronchus.

Adult↗

PubMed1998

A graphical tool for ad hoc query generation.

Medical data are characterized by complex taxonomies and evolving terminology. Questions that clinicians, medical administrators, and researchers may wish to answer using medical databases are not easily formulated as SQL queries. In this paper we describe a graphical tool that facilitates formulation of ad hoc questions as SQL queries. This tool manages multiple attribute hierarchies and creates SQL query strings by navigating through the hierarchies. This interactive tool has been optimized using indexing to improve the overall speed of the query building and the data retrieval process. Indexed queries performed 5 to 100 times faster than query strings. However, query string generation time depends on the size of the taxonomies describing the hierarchies, while the index generation time depends on the size of the data warehouse.

Abstracting and Indexing↗

PubMed1997

Correlation between cervical cytologic results and Gram stain as diagnostic tests for bacterial vaginosis.

OBJECTIVE: Our purpose was to determine the reliability of the Papanicolaou smear in making the diagnosis of bacterial vaginosis with the vaginal Gram stain used as the diagnostic standard. STUDY DESIGN: We conducted a prospective, blinded, cross-sectional study of 210 consecutive patients referred to the Colposcopy Clinic for evaluation of abnormal cervical cytologic results. Each patient had a standard Papanicolaou smear and Gram stain of vaginal discharge. The sensitivity, specificity, positive predictive value, and negative predictive value of the Papanicolaou smear were determined with the Gram stain used as the standard for diagnosis of bacterial vaginosis. RESULTS: Of the 210 patients, 80 (38.1%) had Gram stains that were positive for bacterial vaginosis and 118 (56.2%) had negative Gram stains. Twelve (5.7%) had intermediate Gram stains that were also considered negative. Of the 80 patients with positive Gram stains, 44 had cervical smears consistent with bacterial vaginosis and 36 had negative smears. Of the 130 patients with negative Gram stains, two had a positive cervical smear. Therefore, compared to the Gram stain, cervical cytologic test results had a sensitivity of 55% and a specificity of 98%. The respective positive predictive and negative predictive values were 96% and 78%. CONCLUSION: Compared to Gram stain of vaginal secretions, the cervical Papanicolaou smear has fair sensitivity (55%) and excellent positive predictive value (96%) in diagnosing bacterial vaginosis.

Bacteria, Anaerobic↗

PubMed1997

Confining ingested fluid to the stomach increases water and decreases saline intake in the rat [corrected].

Rats ingest more pure water in a 30-min test following 17 h of water deprivation when the ingested water is confined to the stomach by a pyloric cuff than when it is allowed to enter the duodenum (6). To test the hypothesis that the reduced intake of water under normal drinking conditions is due to postgastric cellular hydration, we allowed rats to ingest pure water or 0.15 M NaCl with the pylorus open and with it closed. When the pylorus was open, rats ingested more NaCl than water. When it was closed, they drank an equal volume of each solution. With the cuff open, the rate of licking pure water began to decline within 3 min of the beginning of the test, an effect that did not occur when the cuff was closed or with NaCl under either test condition. These data support the hypothesis that the intake of water during the first 30 min of access to it following a period of water deprivation is inhibited by the hydration of cells located postgastrically.

Animals↗

PubMed1997

Investigation of multiple dose citalopram on the pharmacokinetics and pharmacodynamics of racemic warfarin.

AIMS: An open, controlled, randomized, crossover study was conducted in healthy males to assess the possible occurrence of a pharmacokinetic/pharmacodynamic interaction between warfarin and the selective serotonin re-uptake inhibitor citalopram. METHODS: Twelve subjects received a single 25 mg dose of racemic warfarin either alone or on Day 15 of a 21-day oral dosing regimen of 40 mg citalopram daily. Blood samples for pharmacokinetic analysis were obtained over a 168 h period after warfarin dosing. The degree of anticoagulation was assessed by the prothrombin time. RESULTS: Citalopram produced no change in the pharmacokinetics of (R)- and (S)-warfarin, indicating that citalopram does not alter the metabolism of warfarin mediated via CYP1A2, CYP3A4 and CYP2C9. Citalopram coadministration resulted in a statistically significant increase in the maximum prothrombin time (R(max); by 1.6 +/- 3.0 s) and the area under the prothrombin time-time curve (AUC(PT); by 5.0 +/- 5.7%). The 90% confidence intervals for R(max) and AUC(PT) ratios (citalopram + warfarin/warfarin alone) were 1.01-1.10 and 1.03-1.07, respectively. CONCLUSIONS: The small increase in prothrombin time observed in this study with coadministration of citalopram and warfarin is not considered to be of importance in the clinical setting.

Adult↗

PubMed1997

Variable memory profiles in Parkinson's disease.

Thirty-nine patients with Parkinson's disease (PD) were categorized into one of three subgroups using discriminant function analysis and three key indices from the California Verbal Learning Test (CVLT). Patients were classified as having one of three memory profiles: (a) a normal memory profile; (b) a memory profile often observed in patients with Huntington's disease (HD); or (c) a memory profile often observed in patients with Alzheimer's disease (AD). Twenty of the patients with PD were classified as having a normal profile, 10 as having an HD profile, and 9 as having an AD profile. The three subgroups did not differ on measures of global cognitive functioning, letter fluency, confrontation naming, or visuo-construction, suggesting that the patients with PD with an AD memory profile were not experiencing AD, per se. These results demonstrate that the memory deficits associated with PD can be similar to those found in patients with either HD or AD, and argues against the notion that the behavioral manifestations of PD are homogeneous.

Age Factors↗

PubMed1997

Missouri's emergency department E-code data reporting: a new level of data resource for injury prevention and control.

This article describes the results of the first statewide external cause of injury (E-code) reporting system that includes emergency department (ED) visits. The results indicate that for every injury-related death, there are 20 hospitalizations and 174 ED visits. Although firearms and motor vehicle crashes were the leading causes of injury-related deaths, falls and motor vehicle crashes were the leading causes of ED visits. An analysis of injuries in one metropolitan statistical area in the state demonstrates similarities and differences from the statewide results. The statewide reporting of cause of injury information in ED visits provides valuable information for injury control efforts.

Adolescent↗

PubMed1997

Reduction of intake in the rat due to gastric filling.

With two exceptions, the literature shows that confining ingested fluid to the stomach of a rat during an intake test had no effect on the volume ingested. In the two exceptions (J. D. Davis and J. L. Sayler, Physiol. Behav. In press. J. A. Deutsch, Handbook of Behavioral Neurobiology. Neurobiology of Food and Fluid Intake, edited by E. M. Stricker. New York: Plenum, 1990, vol. 10), intake with the cuff open was very large, suggesting that, when intake on cuff-open tests exceeds some critical volume, confining all of it to the stomach during the test will reduce intake. To test this, we measured intake of three different solutions known to stimulate large intake with the pylorus open and closed. In cuff-closed tests, intake was less than in cuff-open tests. In cuff-closed tests, rate of licking began to decline within 5-6 min when only about one-quarter of the ultimate contents of the stomach had accumulated, indicating that some signal from the stomach slowed the rate of ingestion before the full capacity of the stomach was reached. This shows that the stomach is sensitive to its contents when it contains only a small proportion of its capacity.

Animals↗

PubMed1996

Persistent placenta increta: a complication of conservative management of presumed placenta accreta.

BACKGROUND: Recent reports have advocated conservative management rather than hysterectomy for placenta increta and its related conditions, placenta accreta and percreta. We report an unusual case of placenta increta in which initial conservative therapy for a presumed placenta accreta failed and hysterectomy was performed 6 months postpartum. CASE: A 32-year-old woman, gravida 2, para 2, was referred 5 months after a repeat cesarean delivery and bilateral tubal interruption for evaluation of an intrauterine mass. A presumed placenta accreta noted at delivery had been managed conservatively. Hysterectomy was performed, and pathologic evaluation was consistent with a retained placenta increta. CONCLUSION: Persistent placental tissue is a potential complication of conservative management of an abnormally adherent placenta.

Adult↗

PubMed1996

Microstructural analysis of the ingestive behavior of the rat ingesting polycose.

A microstructural analysis of the ingestive behavior of rats ingesting seven concentrations of Polycose, was undertaken in an attempt to understand how this complex mix of mono-, di-, and polysaccharides controls their ingestive behavior. In every respect, the pattern of results resembled those obtained using mono- and disaccharides. Over a concentration range of 0.6% to 40%, the volume ingested was a nonmonotonic function of concentration, the duration of the meal was a linear decreasing function of concentration, the initial rate and the rate of decline of the rate of licking were increasing linear functions of the log of the concentration, cluster size was a linear increasing function of log concentration, and the proportion of short intercluster intervals increased linearly with the log of the concentration. These results support the view that the control that Polycose exerts on the ingestive behavior of the rat is very similar to that exerted by mono- and disaccharides.

Animals↗

PubMed1996

Saccharin increases the effectiveness of glucose in stimulating ingestion in rats but has little effect on negative feedback.

To determine if oropharyngeal stimulation contributes to the magnitude of the negative feedback signal during ingestion, we tested rats on a series of solutions that varied in taste intensity but not in nutritive or osmotic properties. To do this, Na saccharin was added to a standard 0.2 M glucose solution in concentrations of 0, 0.25, 0.5, 1, 2, 4, and 8 mM. Nondeprived rats were given free access to these solutions in ascending order of concentration in 30-min tests in test cages with a lickometer that recorded the time of each lick to the nearest msec. The cumulative licking curve for each rat on each test, obtained by cumulating the number of licks in each successive minute during the test, was fit by the least squares method to an exponential function. This provides an estimate of the initial rate of licking and of the rate of decline in the rate of licking. The results were that the volume ingested increased from 6 to 26 ml and the initial rate of licking increased from 50 to 230 licks/min/min over the saccharin concentration range, but the estimates of the rate of decline of the rate of licking remained constant at about 0.06 licks/min over this range. Thus, we found no evidence for an oropharyngeal contribution to the decline in the rate of licking. Changes in the volume ingested depended solely on the initial avidity with which the rats ingested the solution.

Animals↗

PubMed1996

Atovaquone has no effect on the pharmacokinetics of phenytoin in healthy male volunteers.

The potential pharmacokinetic interaction between atovaquone and phenytoin was investigated in 12 healthy male volunteers. Each volunteer received a single 600 mg oral dose of phenytoin in the two treatment periods. On one occasion phenytoin was taken alone and on the other pre-treatment with 2000 mg atovaquone taken as two doses of 1000 mg as a microfluidized suspension. The mean (+/- s.d.) peak plasma concentrations (Cmax), apparent total clearance (CL/F) and terminal half-life (t1/2) for phenytoin when administered alone were 10.6(1.8) mg 1(-1), 24.3 (7.7) ml min-1 and 25(8) h, respectively. When administered together with atovaquone, phenytoin Cmax, CL/F and t1/2,z were 10.9 (2.0) mg 1(-1), 23.8 ml min-1 and 24(6) h, respectively. There were no statistically significant differences in any of these plasma pharmacokinetic parameters. There were also no statistically significant differences in the fraction of circulating drug not bound to plasma protein or urinary excretion of 5-hydroxyphenyl-phenyl-hydantoin. In conclusion, there was no effect of atovaquone on the pharmacokinetics of phenytoin or its major metabolite after a single dose.

Adult↗