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Biomedical subjects

G Hanna

Publications and source records attributed to G Hanna.

At least 19 recordsLinked to original sources
PubMed2002

Prenatal diagnosis of cri du chat (5p-) syndrome in association with isolated moderate bilateral ventriculomegaly.

A case of prenatally detected cri du chat syndrome (5p-) is reported. Amniocentesis was performed following an abnormal ultrasound finding of isolated moderate bilateral ventriculomegaly. The karyotype showed a terminal deletion of the short arm of chromosome 5 including the critical region 5p15 for cri du chat syndrome. This was confirmed by fluorescence in situ hybridisation (FISH). Isolated mild ventriculomegaly may be a non-specific marker for cri du chat syndrome.

Adult↗
PubMed2001

Comparison of orthodox versus off-optical axis endoscopic manipulations.

BACKGROUND: During complex laparoscopic operations, the surgeon often has to use both instruments to one side of the telescope (off-optical axis work). This experimental study was undertaken to compare this orthodox versus the off-optical axis endoscopic manipulations regarding the performance parameters and motion analysis and muscle work of the surgeon's dominant upper limb. METHODS: Ten surgeons participated in the study; each sutured 50-mm enterotomy in pig's small bowel in each of three setups: (1) in-optical axis manipulation (one instrument on either side of the laparoscope) (2) off-optical axis manipulation (both instruments on one side of the laparoscope to the dominant hand of the surgeon), and (3) off-optical axis manipulation both instruments on one side of the laparoscope on the nondominant side). The main outcome measures were the placement error score, execution time, leakage pressure, motion analysis, and telemetric electromyography parameters of the surgeon's dominant upper limb. RESULTS: There was no significant difference in all parameters of performance, muscle work, and fatigue between setup 1 and setup 3. However, marked degradation of all parameters of performance with increased muscle work and fatigue was observed with setup 2 compared to setups 1 and 3. The reason for the deterioration with setup 2 is related to the altered "monitor display angle" which are different from the actual physical angles. With this setup, the instrument-to-target physical angle of 30 degrees appears on the screen as ?30 degrees and this disturbs both the manipulation and the azimuth angles obscuring the needle-tissue entry point. In addition, the instrument casts a shadow on its medial side and this tends to obscure the exact relations between instrument, needlepoint, and the tissue. CONCLUSIONS: Off-optical axis work is a good alternative to the orthodox setup provided the instruments are placed to the nondominant hand. The marked degradation in performance encountered during off-optical axis work to the dominant hand of the surgeon is due to the resulting altered monitor display angles. The importance of these monitor display angles in influencing task performance has been previously overlooked.

Animals↗
PubMed2001

Ergonomic principles of task alignment, visual display, and direction of execution of laparoscopic bowel suturing.

BACKGROUND: Laparoscopic suturing is technically a demanding skill in laparoscopic surgery. Ergonomic experimental studies provide objective information on the important factors and variables that govern optimal endoscopic suturing. Our objective was to determine the optimum physical alignment, visual display, and direction of intracorporeal laparoscopic bowel suturing using infrared motion analysis and telemetric electromyography (EMG) systems. METHODS: Ten surgeons participated in the study; each sutured 50-mm porcine small bowel enterotomies toward and away from the surgeon in the vertical and horizontal bowel plane with either isoplanar (image display corresponds with actual lie of the bowel) or nonisoplanar (bowel displayed horizontally but mounted vertically in the trainer and vice versa) display. The end points were the placement error score, execution time, leakage pressure, motion analysis, and telemetric EMG parameters of the surgeon's dominant upper limb. RESULTS: Suturing was demonstrably easier in the vertical than in the horizontal plane, resulting in a better task quality (placement error score, p < 0.0001; leakage pressure, p < 0.005) and shorter execution time (p < 0.05). Nonisoplanar display of the surgical anatomy degrades performance in terms of both task efficiency and task quality. On motion analysis, a wider angle of excursion and lower angular velocity were observed during the vertical suturing with isoplaner display. Compared to horizontal suturing, supination at the wrist was significantly greater during vertical than horizontal suturing (p < 0.05). Within each category (vertical vs horizontal suturing), the direction of suturing (toward/away from the surgeon) did not influence the extent of pronation/ supination at the wrist. In line with the degraded performance, significantly more muscle work was expended during horizontal suturing. This affected the forearm flexors (p < 0.05), arm flexors and extensors (p < 0.005 and p < 0.05, respectively), and deltoid muscles (p < 0.005) and was accompanied by significantly more fatigue in the related muscles. Small bowel enterotomies sutured toward the surgeon in both the vertical and the horizontal planes exhibited less placement error score than when sutured away from the surgeon, with no significant difference in the motion analysis and EMG parameters. CONCLUSIONS: Optimal laparoscopic suturing (better task quality and reduced execution time) is achieved with vertical suturing toward the surgeon with isoplanar monitor display of the operative field. The poorer task performance observed during horizontal suturing is accompanied by more muscle work and fatigue, and it is not improved by monitor display of the enterotomy in the vertical plane.

Animals↗
PubMed2001

Image display technology and image processing.

Significant developments in video imaging have taken place but further progress is needed to provide images with the right characteristics for optimal interpretation by the operator. The nature and location of the image display in relation to the surgeon and operating field are also important in facilitating image-guided surgery/interventions, and several new technologies are being explored. In the diagnostic field, virtual reality surface anatomical and internal luminal rendering has opened a new chapter in diagnosis, screening, and treatment planning, the potential of which is only just being realized.

Diagnostic Imaging↗
PubMed2001

Genotypic correlates of phenotypic resistance to efavirenz in virus isolates from patients failing nonnucleoside reverse transcriptase inhibitor therapy.

Efavirenz (also known as DMP 266 or SUSTIVA) is a potent nonnucleoside inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) activity and of HIV-1 replication in vitro and in vivo. Most patients on efavirenz-containing regimens have sustained antiviral responses; however, rebounds in plasma viral load have been observed in some patients in association with the emergence of mutant strains of HIV-1. Virus isolates from the peripheral blood mononuclear cells (PBMCs) of patients with such treatment failures, as well as recombinant viruses incorporating viral sequences derived from patient plasma, show reduced in vitro susceptibility to efavirenz in association with mutations in the RT gene encoding K103N, Y188L, or G190S/E substitutions. Patterns of RT gene mutations and in vitro susceptibility were similar in plasma virus and in viruses isolated from PBMCs. Variant strains of HIV-1 constructed by site-directed mutagenesis confirmed the role of K103N, G190S, and Y188L substitutions in reduced susceptibility to efavirenz. Further, certain secondary mutations (V106I, V108I, Y181C, Y188H, P225H, and F227L) conferred little resistance to efavirenz as single mutations but enhanced the level of resistance of viruses carrying these mutations in combination with K103N or Y188L. Viruses with K103N or Y188L mutations, regardless of the initial selecting nonnucleoside RT inhibitor (NNRTI), exhibited cross-resistance to all of the presently available NNRTIs (efavirenz, nevirapine, and delavirdine). Some virus isolates from nevirapine or delavirdine treatment failures that lacked K103N or Y188L mutations remained susceptible to efavirenz in vitro, although the clinical significance of this finding is presently unclear.

Alkynes↗
PubMed1997

Influence of a proton pump inhibitor-based therapy on Helicobacter pylori strain selection.

The influence of the proton pump inhibitor lansoprazole on strain diversity in Helicobacter pylori infected patients was investigated. Multiple isolates of Helicobacter pylori obtained pre- and post-therapy from gastric antral and body biopsies in 22 patients were compared using the random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) for analysis. Post-therapy strains exhibiting novel RAPD-profiles were found in 5 of 22 patients (4 of 11 patients treated with lansoprazole alone and 1 of 11 patients treated with lansoprazole plus amoxicillin). Proton pump inhibition may affect the microecology of the stomach by influencing the colonisation patterns of specific strains.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1996

Interstitial fluid, plasma protein, colloid, and leukocyte uptake into initial lymphatics.

Lymphatics serve to remove from the interstitium a range of materials, including plasma proteins, colloid materials, and cells. Lymph flow rates can be enhanced by periodic tissue compression or venous pressure elevation, but little is known to what degree enhancement of lymph flow affects material transport. The objective was to examine the uptake of plasma proteins, a colloidal perflubron emulsion (LA-11063, mean particle diameter = 0.34 micron), and leukocytes into lymphatics. Prenodal collecting lymphatics in the lower hindlimb of rabbits were cannulated with and without foot massage and after elevation of venous pressure (40 mmHg). The average lymph flow rates were elevated approximately 22-fold by the skin massage but only about threefold by venous pressure elevation. Lymph-to-plasma protein concentration ratio remained unchanged by the massage but decreased significantly after venous pressure elevation. Lymph colloid concentration and leukocyte counts were elevated on average 47 and 8.5 times, respectively, by foot massage, but both decreased after venous pressure elevation. These results suggest that skin movement by massage and elevation of the venous pressure lead to opposite lymph transport kinetics of protein, colloids, and cells. Massage is more effective to enhance material transport out of the interstitium into the initial lymphatics.

Animals↗
PubMed1994

Preclinical and clinical studies on lymph node imaging using perflubron emulsion.

A perflubron emulsion is being developed as a contrast agent to enhance lymph nodes on computed tomography (CT) images. The emulsion is administered by percutaneous injection into the drainage field of the lymph nodes to be imaged. A series of preclinical studies was conducted to investigate the efficacy of the perflubron emulsion for enhancement of lymph nodes on CT images. The effects of dose (0.10 to 0.50 mL), application of massage, and route of administration were investigated in healthy New Zealand white rabbits. Results of these studies demonstrated that doses as low as 0.15 mL were efficacious for consistent enhancement of axillary lymph nodes on CT images after subcutaneous injections in the forepaw. Application of massage to the injection site decreased the time for maximum nodal enhancement from approximately 7 days to 2 days postinjection. A pilot study conducted in 18 healthy, male volunteers indicated dose-related enhancement of axillary lymph nodes on CT images following subcutaneous injections of the emulsion in the hand. Other than mild, transient injection-site discomfort, no clinically significant side effects were observed. These data demonstrate that the perflubron emulsion is safe and can enhance axillary lymph nodes on CT images following injections in the hand.

Analysis of Variance↗
PubMed1994

Intracellular and extracellular transport of perfluoro carbon emulsion from subcutaneous tissue to regional lymphatics.

The aim of this study was to examine the transport mechanism of colloidal particles from subcutaneous tissue to lymphatics. The mechanism of lymph transport was studied in leg prenodal lymphatics of anesthetized rabbits using Imagent LN (60% W/V perfluorooctyl bromide [PFOB] emulsion). Extracellular (dispersed particles) and intracellular (phagocytosed particles by macrophages) PFOB transport was measured in lymph fluid after 0.1ml injection of fluorescently labeled PFOB emulsion into the dorsal skin of the rabbits' foot. Samples were collected from cannulated lower leg prenodal lymphatics. Particles of PFOB emulsion were observed by using a fluorescent technique. The foot/leg were moved passively in a rotary direction at 0.3Hz. Extracellular and intracellular PFOB could be determined in the lymph samples. These findings indicate that both intracellular and extracellular transport mechanisms play a role in the uptake of colloidal particles from interstitial tissue to lymphatics.

Animals↗
PubMed1992

Hyperserotoninemia and antiserotonin antibodies in autism and other disorders.

This study examined the linkage between elevated blood serotonin in autism and the presence of circulating autoantibodies against the serotonin 5HT1A receptor. Information was also obtained on the diagnostic and receptor specificity of these autoantibodies. Blood serotonin was measured as was inhibition of serotonin binding to human cortical membranes by antibody-rich fractions of blood from controls and from patients with childhood autism, schizophrenia, obsessive-compulsive disorder, Tourette's, and multiple sclerosis. The results showed elevated blood serotonin was not closely related to inhibition of serotonin binding by antibody-rich blood fractions. Inhibition of binding was highest for patients with multiple sclerosis and was not specific to the 5HT1A receptor as currently defined. Although inhibition was not specific to autism, the data were insufficient to establish if people with autism differed from normal controls on this measure.

Adolescent↗
PubMed1991

Effects of stimulant medication on learning in children with ADHD.

It is well established that stimulant medication improves classroom manageability and attention in terms of time on task, but does stimulant medication improve learning or long-term academic achievement in children with ADHD? There is no clear evidence that it does, but there are at least two reasons why beneficial effects may be obscured in research studies and clinical practice: (1) Higher-than-optimal doses may be prescribed if behavioral response (rather than cognitive response) is used to titrate the dose, and (2) treatment may be overinclusive if diagnostic groups are targeted in which a significant proportion of cases do not have favorable cognitive responses to medication. This article addresses these two issues and describes a large clinical series of patients who were evaluated using a double-blind medication assessment protocol designed to overcome some of the theoretical deficiencies suggested by these issues.

Achievement↗
PubMed1990

Reduced platelet counts in neonatal respiratory distress syndrome.

Platelet counts were studied in preterm infants with the respiratory distress syndrome (RDS), excluding patients with significant perinatal and postnatal hypoxia. Counts fell to a nadir on day 4 (p less than 0.000). Exploratory analysis indicated that severity of RDS (levels of FiO2 and mean airway pressure), airleak syndrome, grade of intraventricular hemorrhage (IVH) and low platelet count on day 1 were correlated with low platelet count on days 4 and 5. Further analysis by stepwise removal of each variable demonstrated statistically that FiO2 exerted a unique influence on the change in platelet count between day 1 and days 4/5 (p less than 0.002). It is concluded that the severity of RDS is strongly associated with the fall in platelet count in the first few postnatal days. The effect of IVH on platelet count may be secondary to the effect of the RDS.

Age Factors↗
PubMed1988

High-frequency oscillation in the rescue of infants with persistent pulmonary hypertension.

High-frequency oscillatory ventilation (HFOV) was used to treat 41 infants with persistent pulmonary hypertension of the newborn (PPHN). Of the 37 patients who showed early improvement on HFOV, three died. The remaining 34 patients demonstrated, within one hour of the switchover to HFOV, a rise in mean arterial/alveolar oxygen tension ratio (PaO2/PaO2) from 0.093 +/- 0.041 (SD) to 0.132 +/- 0.051 (p less than .001), and a fall in mean PaCO2 from 42 +/- 10 to 34 +/- torr 9 (p less than .01). Mean airway pressure (Paw) fell significantly (p less than .01) within 12 h. The mean duration of conventional mechanical ventilation before starting HFOV was longer in 13 patients who developed bronchopulmonary dysplasia (BPD) than in 21 non-BPD patients (44.7 +/- 32.3 vs. 19.1 +/- 15.6 h, p less than .002), as was the duration of exposure to Paw greater than 15 cm H2O during that treatment mode (31.8 +/- 21.3 vs. 9.5 +/- 6.0 h, p less than .001). HFOV is often effective in the treatment of patients with PPHN, and early initiation of this type of mechanical ventilation may be associated with a reduced incidence of BPD.

Birth Weight↗
PubMedDate not supplied

Evaluating driving performance of outpatients with Alzheimer disease.

BACKGROUND: Alzheimer disease (AD) is a progressive disease, with multiple physiologic, psychologic, and social implications. A critical issue in its management is when to recommend restrictions on autonomous functioning, such as driving an automobile. This study evaluates driving performance of patients with AD and its relation to patient scores on the Mini-Mental State Exam (MMSE). METHODS: This study compared 29 outpatients with probable AD with 21 age-matched control participants on an interactive driving simulator to determine how the two groups differed and how such differences related to mental status. RESULTS: Patients with AD (1) were less likely to comprehend and operate the simulator cognitively, (2) drove off the road more often, (3) spent more time driving considerably slower than the posted speed limit, (4) spent less time driving faster than the speed limit, (5) applied less brake pressure in stop zones, (6) spent more time negotiating left turns, and (7) drove more poorly overall. There were no observed differences between AD patients and the control group in terms of crossing the midline and driving speed variability. Among the AD patients, those who could not drive the simulator because of confusion and disorientation (n = 10) had lower MMSE scores and drove fewer miles annually. Those AD patients who had stopped driving also scored lower on their MMSE but did not perform more poorly on the driving simulator. Factor analysis revealed five driving factors associated with AD, explaining 93 percent of the variance. These five factors correctly classified 27 (85 percent) of 32 AD patients compared with the control group. Of the 15 percent who were improperly classified, there were three false positives (control participants misclassified as AD patients) and two false negatives (AD patients misclassified as control participants). The computed total driving score correlated significantly with MMSE scores (r = -.403, P = 0.011). CONCLUSION: Driving simulators can provide an objective means of assessing driving safety.

Aged↗