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Biomedical subjects

Greg Smith

Publications and source records attributed to Greg Smith.

13 recordsLinked to original sources

A simple method for preparing synthetic controls for conventional and real-time PCR for the identification of endemic and exotic disease agents.

Medical and veterinary diagnostic and public health laboratories world-wide are increasingly being called upon to introduce molecular diagnostic tests for both endemic and exotic diseases. This demand has accelerated following increasing terrorism fears. Ironically these same concerns have lead to tightening of both import and export controls preventing many laboratories, particularly those outside of the United States, from gaining access to positive control material. This in turn has prevented many laboratories from introducing much needed molecular diagnostic tests. We describe here a generic approach for preparing synthetic DNA or RNA control material for use in either TaqMan or conventional PCR assays. The production of synthetic controls using this approach does not require cloning or special equipment or facilities beyond that found in any laboratory performing molecular diagnostics. The approach significantly reduces the possibility of contamination or erroneously reporting false-positive reactions due to contamination from positive control material. Synthetic controls produced using this approach have been employed in all molecular diagnostic tests performed in our laboratory and are used irrespective of whether we possess the organism or not.

Humans↗

Invasion of the central nervous system in a porcine host by nipah virus.

Nipah virus, a newly emerged zoonotic paramyxovirus, infects a number of species. Human infections were linked to direct contact with pigs, specifically with their body fluids. Clinical signs in human cases indicated primarily involvement of the central nervous system, while in pigs the respiratory system was considered the primary virus target, with only rare involvement of the central nervous system. Eleven 5-week-old piglets were infected intranasally, orally, and ocularly with 2.5 x 10(5) PFU of Nipah virus per animal and euthanized between 3 and 8 days postinoculation. Nipah virus caused neurological signs in two out of eleven inoculated pigs. The rest of the pigs remained clinically healthy. Virus was detected in the respiratory system (turbinates, nasopharynx, trachea, bronchus, and lung in titers up to 10(5.3) PFU/g) and in the lymphoreticular system (endothelial cells of blood and lymphatic vessels, submandibular and bronchiolar lymph nodes, tonsil, and spleen with titers up to 10(6) PFU/g). Virus presence was confirmed in the nervous system of both sick and apparently healthy animals (cranial nerves, trigeminal ganglion, brain, and cerebrospinal fluid, with titers up to 10(7.7) PFU/g of tissue). Nipah virus distribution was confirmed by immunohistochemistry. The study presents novel findings indicating that Nipah virus invaded the central nervous system of the porcine host via cranial nerves as well as by crossing the blood-brain barrier after initial virus replication in the upper respiratory tract.

Animals↗

Immunization with modified vaccinia virus Ankara-based recombinant vaccine against severe acute respiratory syndrome is associated with enhanced hepatitis in ferrets.

Severe acute respiratory syndrome (SARS) caused by a newly identified coronavirus (SARS-CoV) is a serious emerging human infectious disease. In this report, we immunized ferrets (Mustela putorius furo) with recombinant modified vaccinia virus Ankara (rMVA) expressing the SARS-CoV spike (S) protein. Immunized ferrets developed a more rapid and vigorous neutralizing antibody response than control animals after challenge with SARS-CoV; however, they also exhibited strong inflammatory responses in liver tissue. Inflammation in control animals exposed to SARS-CoV was relatively mild. Thus, our data suggest that vaccination with rMVA expressing SARS-CoV S protein is associated with enhanced hepatitis.

Animals↗

Entomological investigations in a focus of dengue transmission in Cairns, Queensland, Australia, by using the sticky ovitraps.

Sticky ovitraps (patent pending) were used to sample female Aedes aegypti (L.) weekly in a focus of dengue activity in Cairns, Queensland, Australia. In February 2003, transmission of dengue virus serotype 2 began in the suburb of Parramatta Park, peaking in mid-March 2003. This suburb features many older, unscreened houses with high populations of Ae. aegypti. Highest densities (2-3.5 females per trap per week) were obtained during peak dengue transmission (January and February) before mosquito control was initiated. Beginning in late March, female Ae. aegypti collected in sticky ovitraps were tested for dengue viral RNA by using a TaqMan reverse transcription-polymerase chain reaction assay. Dengue viral RNA was detected in six pools of Ae. aegypti collected in late March. The highest minimum infection rate was 116/1000 mosquitoes. After the initiation of larval control (containers treated with S-methoprene or lambda-cyhalothrin) and adult control (interior harborage sites sprayed with lambda-cyhalothrin) in early March, trap collections dropped to <0.5 per trap per week, and no virus was detected in trapped mosquitoes. Human cases subsequently dropped from a high of seven cases per day in mid-March to only sporadic cases in late April, with the final reported onset of 7 May. Sticky ovitraps have potential as a monitoring device for gravid Ae. aegypti and can be used to assess control efficacy and dengue virus activity. A sticky ovitrap index (mean number of female Ae. Aegypti per trap per week) could be useful in gauging the risk of dengue transmission.

Aedes↗

Susceptibility of pigs and chickens to SARS coronavirus.

An outbreak of severe acute respiratory syndrome (SARS) in humans, associated with a new coronavirus, was reported in Southeast Asia, Europe, and North America in early 2003. To address speculations that the virus originated in domesticated animals, or that domestic species were susceptible to the virus, we inoculated 6-week-old pigs and chickens intravenously, intranasally, ocularly, and orally with 106 PFU of SARS-associated coronavirus (SARS-CoV). Clinical signs did not develop in any animal, nor were gross pathologic changes evident on postmortem examinations. Attempts at virus isolation were unsuccessful; however, viral RNA was detected by reverse transcriptase-polymerase chain reaction in blood of both species during the first week after inoculation, and in chicken organs at 2 weeks after inoculation. Virus-neutralizing antibodies developed in the pigs. Our results indicate that these animals do not play a role as amplifying hosts for SARS-CoV.

Animals↗

Bedside ultrasound to determine prandial status.

The prandial status of ED patients is often unknown. Because a full stomach predisposes patients to aspiration during a variety of urgent interventions, a method of determining the degree of gastric fullness would be of potential clinical importance. The purpose of this single-blind interventional trial was to determine if bedside ultrasound, performed by EPs, could accurately determine prandial status. We enrolled 20 subjects who were randomized to either a fasting or nonfasting group. Three emergency sonographers scanned each subject in both the supine and right lateral decubitus (RLD) positions and independently recorded their determination of the prandial status both before and after ingestion of water. We found that the technique was specific in identifying a full stomach but only moderately reliable in identifying an empty one. Best results (sensitivity S + 86%, specificity S- 70%, accuracy A+ 78%) were achieved only after water ingestion with the patient in the RLD position. We conclude that bedside ultrasound is of only limited value for determining prandial states in the ED setting.

Emergency Medical Services↗

Fryns "Anophthalmia-Plus" syndrome associated with developmental regression.

We report a boy with a nasal deformity, choanal atresia, bifid uvula, severe bilateral microphthalmia and a facial cleft who showed regression of development at the age of 2 years with subsequent improvement. We suggest he represents a further case of the rare Fryns "Anophthalmia-Plus" syndrome.

Abnormalities, Multiple↗

c-Myc-induced extrachromosomal elements carry active chromatin.

Murine Pre-B lymphocytes with experimentally activated MycER show both chromosomal and extrachromosomal gene amplification. In this report, we have elucidated the size, structure, and functional components of c-Myc-induced extrachromosomal elements (EEs). Scanning electron microscopy revealed that EEs isolated from MycER-activated Pre-B+ cells are an average of 10 times larger than EEs isolated from non-MycER-activated control Pre-B- cells. We demonstrate that these large c-Myc-induced EEs are associated with histone proteins, whereas EEs of non-MycER-activated Pre B- cells are not. Immunohistochemistry and Western blot analyses using pan-histone-specific, histone H3 phosphorylation-specific, and histone H4 acetylation-specific antibodies indicate that a significant proportion of EEs analyzed from MycER-activated cells harbors transcriptionally competent and/or active chromatin. Moreover, these large, c-Myc-induced EEs carry genes. Whereas the total genetic make-up of these c-Myc-induced EEs is unknown, we found that 30.2% of them contain the dihydrofolate reductase (DHFR) gene, whereas cyclin C (CCNC) was absent. In addition, 50% of these c-Myc-activated Pre-B+ EEs incorporated bromodeoxyuridine (BrdU), identifying them as genetic structures that self-propagate. In contrast, EEs isolated from non-Myc-activated cells neither carry the DHFR gene nor incorporate BrdU, suggesting that c-Myc deregulation generates a new class of EEs.

Animals↗

FacetMap: A scalable search and browse visualization.

The dominant paradigm for searching and browsing large data stores is text-based: presenting a scrollable list of search results in response to textual search term input. While this works well for the Web, there is opportunity for improvement in the domain of personal information stores, which tend to have more heterogeneous data and richer metadata. In this paper, we introduce FacetMap, an interactive, query-driven visualization, generalizable to a wide range of metadata-rich data stores. FacetMap uses a visual metaphor for both input (selection of metadata facets as filters) and output. Results of a user study provide insight into tradeoffs between FacetMap's graphical approach and the traditional text-oriented approach.

Algorithms↗

A preliminary report on the effects of paclitaxel-impregnated stents on sheep nasal mucosa.

INTRODUCTION: Traditional frontal sinus stents serve only as mechanical devices. It has been proposed that stents also may serve as drug-delivery systems for the topical application of drugs that minimize postoperative scarring. Paclitaxel (Taxol), which has recognized antiscarring effects, may be incorporated via a polymeric formulation into standard rubber stents. The impact of topically applied paclitaxel on the morphology of the nasal mucosa is unknown. METHODS: An adult sheep model was used for this study. A modified rubber T-tube stent (incorporating paclitaxel at varying dosages) was secured to each side of the septum in four animals (eight sides). An unmodified T-tube was placed on each side of one animal, a T-tube with the drug carrier (but no paclitaxel) was placed on each side of the second animal, and T-tubes with varying paclitaxel were placed on each side of the final two animals. After 4 weeks, animals were killed and the nasal mucosa was harvested. The nasal mucosa was sectioned and stained with hematoxylin and eosin. A pathologist then assessed the nasal mucosa for vascular congestion, glandular atrophy, chronic inflammation, mucosal metaplasia, and mucosal ulceration. RESULTS: No consistent histopathological differences were noted in the specimens. All specimens showed varying degrees of vascular congestion, glandular atrophy, chronic inflammation, and mucosal metaplasia; the paclitaxel-impregnated stents were not consistently associated with more severe mucosal injury. Finally, mucosal ulceration was noted to be very rare in all specimens. CONCLUSION: This preliminary report describes the impact of paclitaxel-impregnated stents on sheep nasal mucosa, which tolerated these stents very well. Because paclitaxel minimizes scarring reactions at very low concentrations, paclitaxel-impregnated stents may prove useful in clinical situations in which frontal sinus stenting is deemed necessary. Additional investigations with animal models, as well as clinical trials, may be warranted.

Animals↗