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Biomedical subjects

M Vaughn

Publications and source records attributed to M Vaughn.

At least 19 recordsLinked to original sources
PubMed2005

Determining a diagnostic dose for imidacloprid susceptibility testing of field-collected isolates of cat fleas (Siphonaptera: Pulicidae).

The susceptibility of four laboratory strains of cat fleas, Ctenocephalides felis (Bouche), to imidacloprid was determined by three different laboratories, by using a standardized bioassay protocol. The probit lines generated by the different laboratories were very similar, with LC50 values ranging from 0.32 to 0.81 ppm. Based on these data, a diagnostic dose (DD) of 3 ppm imidacloprid in larval rearing media was provisionally identified for detecting shifts in tolerance, possibly as a consequence of incipient imidacloprid resistance. None of the larvae from the susceptible laboratory strains survived the DD. Eighteen field-collected isolates were evaluated for their susceptibility to imidacloprid and to validate a DD of 3 ppm. Probit lines from 18 field-collected isolates were very similar, with LC50 values ranging from 0.14 to 1.52 ppm. When exposed to the DD, between 3 and 10% of the exposed larvae emerged as adults from only three of the 18 isolates. All other field isolates gave 100% mortality at the DD. Under the criteria established (>5% survivorship at 3 ppm), two isolates would be established on mammalian hosts and more extensive tests conducted to exclude or confirm the presence of resistance. The DD of 3 ppm is robust enough to eliminate most of the susceptible isolates collected until today, yet low enough to identify possible isolates for further testing.

Animals↗
PubMed2002

Development of a larval bioassay for susceptibility of cat fleas (Siphonaptera: Pulicidae) to imidacloprid.

Strategies for controlling cat fleas, Ctenocephalidesfelisfelis (Bouché), have undergone dramatic changes in the past 5 yr. With the advent of on-animal treatments with residual activity the potential for the development of insecticide resistance increases. A larval bioassay was developed to determine the baseline susceptibility of field-collected strains of cat fleas to imidacloprid. All four laboratory strains tested showed a similar level of susceptibility to imidacloprid. Advantages of this bioassay are that smaller numbers of fleas are required because flea eggs are collected for the test. Insect growth regulators and other novel insecticides can also be evaluated. Using a discriminating dose, the detection of reduced susceptibility in field strains can be determined with as few as 40 eggs.

Acetone↗
PubMed2001

hVPS41 is expressed in multiple isoforms and can associate with vesicles through a RING-H2 finger motif.

Vps41p, the protein encoded by the yeast gene VPS41, has been shown to mediate formation of AP-3 transport vesicles from the Golgi apparatus and to facilitate the docking and fusion of lysosomal vesicles. Although both of these activities involve transient association with membrane structures, the mechanisms that mediate those interactions have not been determined. Orthologues of VPS41 have been identified in humans, Drosophila, tomato, and Arabidopsis; the degree of sequence similarity among these genes suggests a highly conserved function. Here we provide evidence that hVps41, the human homologue of Vps41p, is expressed in two isoforms that differ in that one contains a C-terminal RING-H2 sequence motif. Transient expression analysis suggests that this RING-H2 domain is responsible for membrane association. This observation was further supported by the cytosolic localization of site-specific mutants. A truncated construct containing only the hVps41 RING-H2 domain was found to associate with a class of intracellular vesicles that originated from the Golgi and showed partial coincidence with the delta subunit of the adaptor protein complex-3. Together with information from the homologous yeast system, these results suggest that hVps41 may also be involved in the formation and fusion of transport vesicles from the Golgi.

Amino Acid Sequence↗
PubMed2000

Syntaxin 7 and VAMP-7 are soluble N-ethylmaleimide-sensitive factor attachment protein receptors required for late endosome-lysosome and homotypic lysosome fusion in alveolar macrophages.

Endocytosis in alveolar macrophages can be reversibly inhibited, permitting the isolation of endocytic vesicles at defined stages of maturation. Using an in vitro fusion assay, we determined that each isolated endosome population was capable of homotypic fusion. All vesicle populations were also capable of heterotypic fusion in a temporally specific manner; early endosomes, isolated 4 min after internalization, could fuse with endosomes isolated 8 min after internalization but not with 12-min endosomes or lysosomes. Lysosomes fuse with 12-min endosomes but not with earlier endosomes. Using homogenous populations of endosomes, we have identified Syntaxin 7 as a soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) required for late endosome-lysosome and homotypic lysosome fusion in vitro. A bacterially expressed human Syntaxin 7 lacking the transmembrane domain inhibited homotypic late endosome and lysosome fusion as well as heterotypic late endosome-lysosome fusion. Affinity-purified antibodies directed against Syntaxin 7 also inhibited lysosome fusion in vitro but had no affect on homotypic early endosome fusion. Previous work suggested that human VAMP-7 (vesicle-associated membrane protein-7) was a SNARE required for late endosome-lysosome fusion. A bacterially expressed human VAMP-7 lacking the transmembrane domain inhibited both late endosome-lysosome fusion and homotypic lysosome fusion in vitro. These studies indicate that: 1) fusion along the endocytic pathway is a highly regulated process, and 2) two SNARE molecules, Syntaxin 7 and human VAMP-7, are involved in fusion of vesicles in the late endocytic pathway in alveolar macrophages.

Animals↗
PubMed1999

Verbal fluency in children: developmental issues and differential validity in distinguishing children with attention-deficit hyperactivity disorder and two subtypes of dyslexia.

Previous research studies have shown that in adults, verbal fluency is impaired after lesion to the frontal lobes and left temporal lobe. More recently, there have been a few studies reported which indicated that in children, like adults, left hemisphere and frontal lesions result in pronounced effects on verbal fluency. The present study examined developmental differences in verbal fluency within a sample of 130 normal children, aged 6 to 12 years. Additionally, the same verbal fluency test was administered to two subgroups of children with developmental dyslexia and a group of children with attention-deficit/hyperactivity disorder (ADHD). Analysis of variance (ANOVA) revealed significant between-group differences by age in the normal children. Further, ANOVA demonstrated that the verbal fluency measure was clinically useful in differentiating the Language Disorder/Dysphonetic Dyslexic subgroup from the Visual-Spatial/Dyseidetic Dyslexic subgroup and the ADHD group, with the latter two groups performing within the average range.

Journal Article↗
PubMed1997

Intermittent self-catheterization by quadriplegic patients via a catheterizable Mitrofanoff channel.

PURPOSE: Neurogenic bladder due to cervical spinal cord injury is often best managed by clean intermittent catheterization. Limited upper extremity function makes patients with quadriplegia dependent on caregivers for clean intermittent catheterization. The Mitrofanoff umbilical appendicovesicostomy provides easy access to the bladder in patients with all types of access difficulty. We evaluated the Mitrofanoff umbilical appendicovesicostomy in 7 patients with quadriplegia. MATERIALS AND METHODS: Four men and 3 women with cervical spinal cord injury underwent the Mitrofanoff umbilical appendicovesicostomy with appendix (5) or ileum (2). RESULTS: All patients are continent and able to self-catheterize via the umbilical stoma. In 1 patient with an ileal Mitrofanoff umbilical appendicovesicostomy umbilical incontinence was repaired surgically and stomal stenosis developed in 1, which required stomal revision. All patients use the stoma regularly. Four patients have moved out of care facilities and are living more independently. CONCLUSIONS: The Mitrofanoff catheterizable channel is a valuable option for bladder management in patients with quadriplegia. Clean intermittent self-catheterization allows these patients independent function and facilitates their return to productive lives outside care facilities.

Adult↗
PubMed1995

Relation between pulmonary venous flow and pulmonary wedge pressure: influence of cardiac output.

Multiple factors affect the systolic and diastolic components of pulmonary venous flow. It has been suggested that left ventricular function might influence the effects of filling pressures on indexes of pulmonary venous flow. The present study was designed to evaluate the effect of the pulmonary wedge pressures, left ventricular function, and cardiac output on the pulmonary vein flow pattern. Forty-five patients undergoing cardiac surgery were included in this study. Pulmonary venous flow and mitral flow variables were obtained by transesophageal echocardiography with hemodynamic variables obtained simultaneously. In the total group, there was no consistent relation between the pulmonary venous flow or the mitral flow parameters and the capillary wedge pressures. When patients were grouped according to normal (> 2.2 L/min/m2) or low (< 2.2 L/min/m2) cardiac index, a significant and positive relation was found between the systolic component of the pulmonary venous flow and the pulmonary wedge pressure in patients with normal cardiac index (r = 0.69; p = 0.003). Conversely, in patients with low cardiac index there was also a significant although negative correlation between the systolic velocity integral and the pulmonary wedge pressure (r = -0.58; p < 0.001). In conclusion, the systolic component of the pulmonary venous flow correlates closely and significantly with the capillary wedge pressures. The direction of this relation depends to a large extent on the total cardiac output and to a lesser extent on the left ventricular systolic function as assessed by the ejection fraction.

Adult↗
PubMed1995

Nephrectomy combined with lower abdominal extraperitoneal ureteral bladder augmentation in the treatment of children with the vesicoureteral reflux dysplasia syndrome.

Ureterocystoplasty is a novel procedure well suited for treating children with megaureters and small or noncompliant bladders. It combines the benefits of enterocystoplasty without many of its drawbacks. We performed nephrectomy through a posterior approach with extraperitoneal ureteral augmentation in 6 patients with bladder neck obstruction and reflux into a nonfunctioning kidney (the vesicoureteral reflux dysplasia/vesicoureteral reflux nonfunctioning kidney syndrome). In all patients capacity increased significantly. Bladder pressure at capacity decreased in patients who were evaluated by urodynamics postoperatively, and continence was achieved or preserved. There were no complications and hospital stay was short. Nephrectomy via a posterior approach with extraperitoneal ureteral augmentation is an appropriate procedure for children with the vesicoureteral reflux dysplasia syndrome. It should be considered for all such patients before nephroureterectomy is done and irreversible loss of valuable compliant native urothelium occurs.

Adolescent↗
PubMed1995

Long-term results of the artificial urinary sphincter in male patients with neurogenic bladder.

The records of patients who received an artificial urinary sphincter at the University of Minnesota were reviewed. A total of 19 patients fulfilled the following criteria: male gender, neurogenic sphincteric incompetence, no previous surgery on the bladder neck, myelodysplasia and more than 5 years of followup. Mean age at the time of implantation was 8 years, mean age at the last followup was 16.5 years and mean followup was 8 years. At the last followup 16 patients (84.2%) were continent and 3 were expected to regain continence after revision or bladder augmentation. At the last followup 78.9% of the patients were on anticholinergic medications and 73.8% voided by clean intermittent catheterization. A fourth of the patients voided spontaneously. The annual revision rate was 0.2 revisions per patient. Seven patients (36.8%) have undergone or will require bladder augmentation. Upper tract dilatation developed in 2 patients and the function of 1 of 38 renal units at risk was lost. We conclude that the artificial urinary sphincter is an excellent modality for the initial surgical treatment of neurogenic sphincteric incompetence in male patients. Careful patient selection and lifelong surveillance are essential to success and safety.

Adolescent↗
PubMed1993

Usefulness of transesophageal echocardiography in unexplained cerebral ischemia.

Two-hundred seventy consecutive patients with "unexplained cerebral ischemia" were studied with transesophageal echocardiography to determine the value of this test in identifying potential cardiac sources of cerebral embolism. The findings of this group were compared with those of 772 consecutive patients undergoing transesophageal echocardiographic evaluation for indications other than cerebral ischemia. This study also examined this group of patients with unexplained cerebral ischemia to determine differences in relation to underlying cardiac rhythm and patient age. Intracardiac thrombus, atrial septal aneurysm, patent foramen ovale, spontaneous left atrial contrast and protruding debris in the thoracic aorta were found more often in patients with unexplained cerebral ischemia. Wall motion abnormalities of the left ventricle, as well as mild to moderate valvular lesions including mitral valve prolapse, were found to be similar in both groups. Spontaneous left atrial contrast, as well as mild to moderate valvular abnormalities, were found more often in patients with atrial fibrillation (22% of the group with unexplained cerebral ischemia). However, the presence of intracardiac thrombus was no more frequent in patients with atrial fibrillation than in those with normal sinus rhythm. Patients aged > 50 years were found to have atrial fibrillation and larger left atrial size more often than their younger cohorts, as well as a greater incidence of valvular abnormalities and left ventricular wall motion abnormalities. Mitral valve prolapse was seen more frequently in the younger cohort of patients.

Adolescent↗
PubMed1989

The effect of progressive muscle relaxation on stress among clerical workers.

Stressors such as the lack of challenge and opportunities for advancement, and the inability to influence the organization help explain why clerical work is considered a demanding and stressful occupation. One stress management technique which may be effectively implemented on the job for clerical workers is progressive muscle relaxation. In primary prevention, nursing intervention strives to reduce the effects of harmful stress by identifying and assessing stressors and then implementing measures to strengthen lines of defense.

Adult↗
PubMed1985

Characterization of human IgG Fc receptors.

A murine monoclonal antibody, KuFc79, has been developed that reacts with human IgG Fc receptors on monocytes, B lymphocytes, and granulocytes. The specificity of KuFc79 for Fc receptors was demonstrated by the ability of Fab fragments to block Fc-mediated phagocytosis by monocytes. This finding was further substantiated by the decrease of KuFc79 binding to monocytes and granulocytes (58 and 70%, respectively) after modulation of surface IgG receptors with aggregated IgG. In addition, Fab KuFc79-conjugated Sepharose was used to isolate functional IgG Fc-binding molecules from soluble extracts of the human monocyte-like cell line U937. By immunoprecipitation, it was further shown that KuFc79 immunoprecipitated molecules of 42,000 and 70,000 daltons from U937 and a human lymphoblastoid cell line, SB. A lower m.w. species of approximately 33,000 was also precipitable from granulocytes. Extensive microheterogeneity of these molecules was noted by isoelectric focusing, which appears to be due to differential sialation.

Animals↗