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Biomedical subjects

G Davis

Publications and source records attributed to G Davis.

At least 55 records · Page 3Linked to original sources

Gamma oscillations and object processing in the infant brain.

An enduring controversy in neuroscience concerns how the brain "binds" together separately coded stimulus features to form unitary representations of objects. Recent evidence has indicated a close link between this binding process and 40-hertz (gamma-band) oscillations generated by localized neural circuits. In a separate line of research, the ability of young infants to perceive objects as unitary and bounded has become a central focus for debates about the mechanisms of perceptual development. Here we demonstrate that binding-related 40-hertz oscillations are evident in the infant brain around 8 months of age, which is the same age at which behavioral and event-related potential evidence indicates the onset of perceptual binding of spatially separated static visual features.

Electroencephalography↗

Dobutamine stress echocardiography in patients undergoing liver transplantation evaluation.

BACKGROUND: Coronary artery disease has an important impact on perioperative morbidity and mortality in patients undergoing liver transplantation. To assess the role of dobutamine stress echocardiography (DSE) in these patients, DSE was included in the preoperative evaluation. METHODS: Patients under consideration for liver transplantation underwent detailed clinical history, electrocardiography, and echocardiography. Patients with documented coronary disease or symptoms of myocardial ischemia underwent angiography. The remaining patients with cardiac risk factors, atypical chest pain, or age > or = 60 years underwent DSE. RESULTS: These 121 patients (77 men and 44 women) ranged in age from 34 to 73 years (mean 53). Among the 61 patients who underwent liver transplantation, DSE was normal in 25, nondiagnostic in 34 because of inadequate heart rate response, and abnormal in two patients. Major perioperative events occurred in eight patients, all with normal or nondiagnostic DSE studies (negative predictive value 86%). CONCLUSIONS: In patients with low to moderate risk of cardiac disease, DSE performed as part of an evaluation for liver transplantation is a poor predictor of major perioperative events.

Adult↗

Reappraising the apparent costs of attending to two separate visual objects.

Support for object-based accounts of visual attention has been drawn from several different types of effect. One effect is found when observers try to restrict their attention to a particular region of a display. Other regions belonging to the same object are often selected as well, suggesting that attention spreads spatially over entire objects. Another effect is found when judging two visual attributes; performance is often less efficient when the attributes belong to separate objects rather than both belonging to a single object. This latter effect has been taken to imply that only one segmented object can be attended at a time. However, it may instead merely be a variant of the first effect. If, as we assume here, attention spreads to task-irrelevant regions of relevant objects, it will encompass a larger spatial region and more information when judging attributes of two objects rather than one. Here we compared judging one versus two objects, while manipulating whether the two objects occupied a wider extent than the single object condition (as in previous work), or not. Costs were found for judging two objects versus one only when together they occupied a wider spatial extent. We conclude that reported difficulties in attending two objects may be due to attention spreading across the entire spatial extent of objects when judging their parts, rather than a fixed inability to process more than object at a time.

Adult↗

Increased risk of cardiovascular disease in newly diagnosed type 2 diabetic patients in a primary health care center in Trinidad.

The prevalence of cardiovascular diseases (CVD) has increased sharply in the developing countries and because Type 2 diabetic patients are at increased risk for CVD, we assessed CVD risk factors in newly diagnosed Type 2 diabetic patients presenting in a primary health care center in Trinidad. Fasting and 2 h postprandial blood samples were collected from 387 (269 females, 118 males) newly diagnosed Type 2 diabetic patients (mean age: 53.1+/-6.6 years) for the determination of plasma glucose, creatinine, cholesterol (chol), triglyceride (TG) and % glycated hemoglobin (HbA(1c)) concentrations. Blood pressure and anthropometric indices were also measured. There were high prevalence rates of obesity (37%), overweight (35%), hypertension (21%), hypercholesterolemia (25%) and hypertriglyceridemia (22.3%) among the patients and these were significantly higher in women than men (P<0.001). Patients of Indian descent had a significantly higher prevalence of diastolic hypertension and hypertriglyceridemia compared with patients of African origin or mixed race (P<0.001). In comparison with males, female diabetic patients were at greater risk of cardiovascular morbidity and mortality. Early detection of CVD risk factors and treatment, particularly in women, may be beneficial management strategy in all local diabetic clinics in Trinidad.

Black People↗

Drosophila Futsch/22C10 is a MAP1B-like protein required for dendritic and axonal development.

Here we report the description of the Drosophila gene futsch, which encodes a protein recognized by the monoclonal antibody 22C10 that has been widely used to visualize neuronal morphology and axonal projections. The Futsch protein is 5327 amino acids in length. It localizes to the microtubule compartment of the cell and associates with microtubules in vitro. The N- and C-terminal domains of Futsch are homologous to the vertebrate MAP1B microtubule-associated protein. The central domain of the Futsch protein is highly repetitive and shows sequence similarity to neurofilament proteins of which no Drosophila homologs have been reported. Loss-of-function analyses demonstrate that during embryogenesis Futsch is necessary for dendritic and axonal growth. Gain-of-function analyses demonstrate a functional interaction of Futsch with other MAPs. In addition, we show that during development, futsch expression is negatively regulated in nonneuronal tissues.

Aging↗

Consensus and comprehensive linkage maps of bovine chromosome 7.

The objective of this project was to integrate the currently available linkage maps for bovine chromosome 7 (BTA7) by combining data sets from eight research groups. A total of 54 unique markers were typed in eight pedigrees. Multilocus linkage analysis with CRI-MAP produced a bovine chromosome 7 consensus framework map of 27 loci ordered with odds greater than 1000:1. Furthermore, we present a bovine chromosome 7 comprehensive map integrating 54 loci. The locus order is in general agreement with the recently published linkage maps except for one discrepancy. The order of loci BM9289, BMS713, and ILSTS001 was reversed in the consensus framework map relative to the published USDA-MARC bovine chromosome 7 linkage map.

Animals↗

Long-term renal effects of unilateral ureteral obstruction and the role of endothelin.

BACKGROUND: Angiotensin II (Ang II) and endothelin (ET) are involved in the alteration of renal function in unilateral ureteral obstruction (UUO). The renal response to Ang II following the reversal of a 24-hour UUO and the effect of ET blockade by bosentan during the time of obstruction were investigated. METHODS: Following blockade of the endogenous production of Ang II by captopril, the renal response to Ang II was studied in rats 15 to 18 days after a 24-hour UUO (N = 10) or a sham operation (N = 9) both with (N = 10) and without (N = 8) bosentan treatment in the periobstruction period. Similar studies were performed in another group (N = 9) two months following the reversal of obstruction. RESULTS: In the sham-operated group, Ang II reduced renal blood flow (RBF) by 42 +/- 9% (P < 0.01), glomerular filtration rate (GFR) by 30 +/- 8% (P < 0.01), urine volume (UV) by 44 +/- 9% (P < 0.001), and absolute (UNaV) and fractional sodium excretion (FENa) by 52 +/- 9% (P < 0.001) and 33 +/- 9% (P = 0.054), respectively. In the previously obstructed kidney, Ang II did not change RBF but increased GFR by 106 +/- 40% (P < 0.01), UV by 75 +/- 21% (P < 0.001), UNaV by 190 +/- 60% (P < 0.001), and FENa by 40 +/- 13% (P < 0.05). Bosentan treatment in the obstructed group prevented these Ang II-induced effects and did not have any effect on the sham-operated kidney. Two months following reversal of the obstruction, the response of the kidney was similar to that of the control kidney. CONCLUSION: Twenty-four-hour UUO results in a temporary abnormality in the renal response to Ang II, which is due, in part, to the actions of ET at the time of obstruction.

Angiotensin II↗

Patients with a prior failed transvaginal cerclage: a comparison of obstetric outcomes with either transabdominal or transvaginal cerclage.

OBJECTIVE: Our purpose was to compare the incidence of preterm birth after a prior failed vaginal cerclage in patients who had a subsequent transabdominal or a transvaginal cerclage. STUDY DESIGN: We conducted a retrospective cohort study of singleton pregnancies in women who had undergone (9-14 weeks) either a transabdominal or a transvaginal prophylactic cerclage after >/=1 prior failed transvaginal cerclage. Prior failed transvaginal cerclage was defined as a preterm birth at <33 weeks' gestation in the immediate prior pregnancy despite a transvaginal cerclage. All transabdominal cerclage procedures were performed by a single attending physician (George Davis, DO). Patients with a cervix too short for transvaginal cerclage placement, placenta previa, or major fetal anomalies were excluded. Primary outcome was preterm birth at <35 weeks' gestation. RESULTS: Forty transabdominal and 24 transvaginal cerclage pregnancies were analyzed. These 2 groups were similar in race and payer status but differed in age (34.0 +/- 4.2 vs 31.3 +/- 4.6 years, respectively; P =.01). The transabdominal cerclage group had more prior failed cerclage procedures per patient (1.8 +/- 1.0 vs 1.1 +/- 0.3; P =.02) and more prior 14- to 24-week spontaneous abortions per patient (2.4 +/- 1.3 vs 1.5 +/- 1.0; P =.02) than the transvaginal cerclage group. Preterm delivery at both <35 and <33 weeks' gestation was less common in the transabdominal cerclage group (18% vs 42%, P =.04; 10% vs 38%, P =.01; respectively) than in the transvaginal cerclage group. Gestational age at delivery was 36. 3 +/- 4.1 weeks in the transabdominal cerclage group and 32.8 +/- 8. 6 weeks in the transvaginal cerclage group (P =.03). Preterm premature rupture of membranes also occurred less often in the transabdominal cerclage group than in the transvaginal cerclage group (8% vs 29%, P =.03). CONCLUSION: In patients with a prior failed transvaginal cerclage, transabdominal cerclage is associated with a lower incidence of preterm delivery and preterm premature rupture of membranes in comparison with transvaginal cerclage.

Abdomen↗

Intra- and post-operative assessment of renal cortical perfusion by laser Doppler flowmetry in renal transplantation in the rat.

Renal blood flow (RBF) in the period immediately following transplantation has an important prognostic value. Here we report for the first time on the use of laser Doppler flowmetry (LDF) for the measurement of renal cortical perfusion (RCP) during all the important steps in renal transplantation. Left orthotopic kidney transplantation was performed in Lewis rats (n = 14) after 2 h of cold ischaemia and preservation in EuroCollins solution. Under baseline conditions, RCP in the donor and recipient kidneys were similar with a coefficient of variability of 11 and 12%, respectively. There was a progressive increase in RCP during the first 60 min after transplantation with a return to normal values 2 weeks later. In conclusion, LDF provides a rapid and continuous measure of RCP without interference to the operative site and may prove a useful tool for the measurement of RBF during kidney transplantation.

Animals↗

The role of endothelin in early renal cortical reperfusionin renal transplantation.

The role of specific endothelin receptors in the early renal reperfusion and long-term survival in renal transplantation was investigated in Lewis rats. Left renal transplantation was performed following 2 h cold ischaemia without and with ET(A) receptor antagonism and following 16 h cold ischaemia with no treatment, with ET(A) receptor antagonism and with ET(B) receptor antagonism. The ET(A) and ET(B) receptor antagonists, BQ-610 and A-192621 respectively, were added to the preservation solution. Renal cortical perfusion (RCP) was measured postoperatively using laser Doppler flowmetry. All rats in the 2-hour groups survived for 15 days. Animals in the untreated 16-hour group or in the A-192621-treated group died between days 3 and 6 after surgery. Fifty percent of the rats in the 16-hour and BQ-610-treated group died between days 4 and 7 after surgery while the other 50% survived for 15 days. Survival rates correlated well with both the postoperative serum creatinine and the recovery of RCP. We conclude that addition of an ET(A) receptor antagonist to the preservation solution improves renal reperfusion and long-term survival following prolonged ischaemia, whereas ET(B) receptor antagonism does neither.

Animals↗

CD45 tyrosine phosphatase inhibitory components from Aspergillus niger.

Two inhibitors of CD45 tyrosine phosphatase, dihydrocarolic acid (1) and penitricin D (2), were isolated from a fermentation broth of the fungus Aspergillus niger and purified by HSCCC (high speed countercurrent chromatography) followed by HPLC. The structures were determined by NMR. The inhibitory activities of both compounds were specific to tyrosine phosphatases.

Aspergillus niger↗

Self-administered topical imiquimod treatment of vulvar intraepithelial neoplasia. A report of four cases.

BACKGROUND: Vulvar intraepithelial neoplasia (VIN) generally can be classified into viral and nonviral etiologies. The histopathologic diagnosis is often separable into basaloid and warty types. A large percentage of VIN lesions have been shown to harbor human papillomavirus (HPV), principally type 16. Imiquimod, an immune response modifier, has been shown to be safe and effective for the treatment of external and perianal genital warts caused by HPV. CASES: Four cases occurred of clinical and histopathologically diagnosed viral VIN 3. An imiquimod treatment protocol, previously used in a study of this drug for the treatment of external genital warts, was followed. Imiquimod 5% cream was patient applied three times per week until all lesions cleared, for a maximum of 16 weeks. CONCLUSION: Imiquimod may be an effective treatment modality for viral VIN 3 in the future.

Adjuvants, Immunologic↗

Early metabolic defects for developing diabetes mellitus among offspring of patients with type 2 diabetes are independent of gender.

The aim of the study was to investigate if the female offspring of patients with Type 2 diabetes have more metabolic defects for developing diabetes mellitus than their male counterparts. Thirty-four offspring (10 males, 24 females) of patients with Type 2 diabetes mellitus aged 28.9 +/- 1.5 years (mean +/- SEM) underwent a standard oral glucose tolerance tests (OGTT; 75 g glucose in 300 ml water). Anthropometric indices, plasma lipids and blood pressure were measured while insulin resistance (IR) and sensitivity (%S) were assessed using the Homeostasis Model Assessment (HOMA) method. All the offspring had normal glucose tolerance but high HOMA-derived IR values (27.2 +/- 4.2 vs. 22.5 +/- 2.7 pmol/mmol/l, p > 0.05) and low %S (48.1 +/- 5.1 vs. 50.6 +/- 3.9%, p > 0.05), all of which did not differ on gender comparisons. Multiple linear regression analyses suggest that gender had no influence on the outcome of the result (p = 0.37). Again, body mass index (BMI), fasting serum insulin, plasma glucose, triglyceride, total cholesterol, HDL-cholesterol and LDL-cholesterol were all similar in both genders (p > 0.05). The results suggest that though the offspring manifested metabolic defects for developing diabetes in later life, this susceptibility is independent of gender in the population studied. Further studies with a larger sample size are warranted to confirm these findings in this population.

Adult↗

Retrograde intubation dacryocystorhinostomy for proximal and midcanalicular obstruction.

OBJECTIVE: Retrograde intubation of canaliculi during dacryocystorhinostomy can restore canalicular patency in cases otherwise managed with bypass tubes. The surgical technique and success for this procedure are discussed. DESIGN: A retrospective, noncomparative case series with clinic or telephone interview for long-term follow-up of patients' symptoms. PARTICIPANTS: One hundred two patients who had undergone this particular lacrimal drainage surgery at Moorfields Eye Hospital between 1992 and 1997. INTERVENTION: All patients underwent a dacryocystorhinostomy and retrograde canaliculostomy while under general anesthetic. MAIN OUTCOME MEASURES: Relief or reduction of epiphora and discharge. RESULTS: One hundred twenty-three lacrimal systems of 102 patients were included. There were 53 females and 49 males, with ages at surgery ranging from 6 to 83 years (mean, 49 years). The etiology was idiopathic (30%), herpetic canaliculitis (24%), punctal agenesis (18%), and trauma (11%); less-common causes included dacryocystitis, Stevens-Johnson syndrome, eczema, and prior radiation therapy. Both upper and lower canalicular systems were involved in the majority (73%) of patients, and in 13 (11%) systems a dacryocystorhinostomy had previously been performed. The silicone tube was placed for a mean of 2 months (range, 1 week-9 months), and the mean postoperative follow-up was 8 months (range, 2-24 months). Epiphora subjectively improved in 90 (73%) of 123 systems, of which 27 (22%) of 123 were asymptomatic. In 33 systems (27%) in which epiphora persisted, 14 (11%) have undergone closed placement of a Jones canalicular bypass tube with control of symptoms. CONCLUSIONS: Retrograde canaliculostomy and intubation can spare a significant number of patients the long-term inconvenience of Jones tubes. Failure of this technique does not, however, compromise or complicate the future placement of a bypass tube.

Adolescent↗

Longitudinal study of predictive factors for periodontal disease and tooth loss.

Longitudinal assessment of risk factors for periodontal disease is necessary to provide evidence that a putative risk factor or risk indicator is a true risk factor. The purpose of the present study was to explore longitudinally a variety of markers as possible periodontal risk factors in subjects with little or no periodontal disease at baseline. 415 subjects with mild or little periodontal disease were examined: medical and dental history; socioeconomic profile, clinical measurements, microbial samples and radiographic assessment of bone height were performed at baseline, and at a follow-up examination 2 to 5 years later. Mean probing pocket depth (PPD) at baseline was 1.99+/-0.37 mm while mean overall change was 0.1 mm which amounts to an annual rate of 0.04 mm. Overall mean clinical attachment level (1.75+/-0.6 mm) at baseline resulted in mean attachment change of 0.28 mm (0.12 mm annually). Alveolar crestal height (ACH) at baseline (mean 2.05+/-0.85 mm) resulting in a mean net loss of 0.1 mm. Approximately 10% of all sites presented for the second visit with attachment loss exceeding the threshold (4.4% annually), while only 2.2% of all sites exhibited attachment gain (0.88% annually). Older individuals exhibited greater mean bone loss but the least amount of attachment loss. Current smokers exhibited greater disease progression compared to non-smokers. Tooth morbidity (0.17 teeth/patient/year) was associated with greater baseline CAL and ACH loss, and an assortment of systemic conditions. Subjects who harbored Bacteroides forsythus (Bf) at baseline had greater loss in ACH; likewise, these subjects experienced greater proportions of losing sites and twice as much tooth mortality compared to Bf-negative patients. Baseline clinical parameters correlated strongly with the outcome, i.e., subjects with deeper mean pocket depth at baseline exhibited greater increase in pocket depth overtime; while subjects with greater attachment loss at baseline exhibited greater attachment loss between the 1st and 2nd visits.

Adult↗

An interactive, computer-based program to educate patients about genital herpes.

BACKGROUND AND OBJECTIVES: Education and counseling constitute a substantial portion of management of patients with genital herpes. Innovative methods for education about genital herpes are needed. GOAL: To test the ability of an interactive, computer-based program to educate patients about genital herpes. STUDY DESIGN: Persons seeking care at five urban offices were asked to participate. A knowledge test about genital herpes was administered before and after participation. Participants' satisfaction was assessed with a questionnaire. RESULTS: Four hundred thirty-five participants enrolled, and 428 completed the herpes knowledge test. Of six questions evaluated, a statistically significant increase in the proportion of correct answers was noted on five of six questions. Fifty-one percent of participants answered all the questions correctly after the program, compared with 39% before the program. Satisfaction with the program was very high. CONCLUSIONS: Innovative, computer-based programs can provide education and assist in the management of chronic sexually transmitted infections.

Adolescent↗