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Biomedical subjects

C Griffith

Publications and source records attributed to C Griffith.

17 recordsLinked to original sources
PubMed2006

A laboratory evaluation of the decontamination properties of microfibre cloths.

Standards of cleanliness in health care continue to attract attention. Effective cleaning requires the input of energy, and microfibre cloths may help in the physical removal of soil. The ability of these cloths to remove organic soil (measured by ATP) and bacteria was compared with paper towel and a conventional cloth in controlled wet and dry conditions. When used wet on a dry surface, the cleaning ability of six different microfibre cloths was variable, and in most cases, not significantly better than paper towel or a conventional cloth. One type of microfibre cloth did perform significantly better than the others and paper towel in reducing both organic soil and microbial load. When used dry on a dry surface, there was no significant difference between the cloths, and none of the cloths reduced microbial and organic bioburden effectively. The ability of the cloths to recontaminate the surface was also tested, and some of the microfibre cloths transferred significantly less organic debris and micro-organisms back to the surface than other cloths. Different makes of microfibre cloths have different characteristics, and the name 'microfibre' should not imply superior cleaning efficacy.

Colony Count, Microbial↗
PubMed2006

Brain volume measurements in patients with human T-cell lymphotropic virus-1-associated tropical spastic paraparesis.

Human T-cell lymphotropic virus (HTLV)-1 is associated with a chronic progressive neurologic disease known as HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) that affects 0.2% to 3% of HTLV-1-infected people. The authors aimed at exploring, in vivo, whether brain volume reduction occurs in patients with HAM/TSP through the use of magnetic resonance imaging (MRI). T1 pre/postcontrast spin echo-weighted images (WIs) and T2WIs of the brain were obtained in 19 HAM/TSP patients and 14 age-and sex-matched healthy volunteers. Both patients and healthy individuals were imaged at a 1.5-Tesla magnet by employing a conventional head coil. Focal T1 and T2 abnormalities were calculated and two measurements of brain parenchyma fraction (BPF) were obtained by using SIENAx (Structural Image Evaluation,using Normalisation, of Atrophy; University of Oxford, Oxford, UK) and MIPAV (Medical Image Processing, Analysis, and Visualization; National Institutes of Health, Bethesda, USA) from T1WIs. No significant differences in BPF were found between patients and healthy subjects when using either SIENAx or MIPAV. Analysis of individual patients detected that BPF was lower by 1 standard deviation (SD) relative to patients' average BPF in one patient. The authors conclude that reductions in BPF do not occur frequently in patients with HAM/TSP. However, the authors believe that one individual case of significant brain atrophy raises the question as to whether atrophy selectively targets the spinal cord of HAM/TSP patients or may involve the brain as well. A larger patient population analyzing regional brain volume changes could be helpful in determining whether brain atrophy is a marker of disease in patients with HAM/TSP.

Adult↗
PubMed2003

The microbiological quality of washing-up water and the environment in domestic and commercial kitchens.

AIMS: To determine the microbiological quality of washing-up water and the environment in domestic and commercial kitchens. METHODS AND RESULTS: Chicken meals were prepared by people without food safety training in their own kitchen (n = 52) or by trained staff in a commercial kitchen (n = 10). Study participants then washed-up, cleaned the kitchen and completed a food hygiene questionnaire. The temperature and microbiological quality of the washing-up water, and the presence of pathogens in dishcloths, tea towels and other kitchen samples was determined. Of the raw chickens used in meal preparation, 96 and 13% were naturally contaminated with Campylobacter or Salmonella spp., respectively. In domestic kitchens, two of 45 sponges, dishcloths or scourers and one of 32 hand- or tea towels were contaminated with Campylobacter after washing-up and cleaning but none of the tap or sink swabs yielded pathogens. The mean washing-up water temperature in the domestic kitchens was 40.7 degrees C, whereas in the commercial kitchen it was 44.7 degrees C (P = 0.04). Study participants who used hotter water (>/=40 degrees C) had lower levels of bacteria in their washing-up water. The aerobic plate counts of the washing-up water samples in domestic homes were usually between 105 and 106 CFU ml-1 but those associated with the commercial kitchen were consistently lower (P = 0.01). Despite this, Campylobacter was detected in one of 10 washing-up water samples from the commercial kitchen but in none of the samples from domestic kitchens. CONCLUSIONS: Pathogenic microorganisms can be recovered relatively frequently from the kitchen environment. SIGNIFICANCE AND IMPACT OF STUDY: By identifying factors that affect the number of microorganisms in washing-up water and the kitchen environment, evidence-based recommendations on implementing domestic food hygiene can be made.

Animals↗
PubMed2002

Combined MR imaging and numerical simulation of flow in realistic arterial bypass graft models.

We report methods for (a) transforming a three-dimensional geometry acquired by magnetic resonance angiography (MRA) in vivo, or by imaging a model cast, into a computational surface representation, (b) use of this to construct a three dimensional numerical grid for computational fluid dynamic (CFD) studies, and (c) use of the surface representation to produce a stereo-lithographic replica of the real detailed geometry, at a scale convenient for detailed magnetic resonance imaging (MRI) flow studies. This is applied to assess the local flow field in realistic geometry arterial bypass grafts. Results from a parallel numerical simulation and MRI measurement of flow in an aorto-coronary bypass graft with various inlet flow conditions demonstrate the strong influence of the graft inlet waveform on the perianastomotic flow field. A sinusoidal and a multi harmonic coronary flow waveform both with a mean Reynolds number (Re) of 100 and a Womersley parameter of 2.7 were applied at the graft inlet. A weak axial flow separation region just distal to the toe was found in sinusoidal flow near end deceleration (Re = 25). At the same location and approximately the same point in the cycle (Re = 30) but in coronary flow, the axial flow separation was stronger and more spatially pronounced. No axial flow separation occurred in steady flow for Re = 100. Numerical predictions indicate a region in the vicinity of the suture line (where there is a local narrowing of the graft) with a wall shear magnitude in excess of five times that associated with fully developed flow at the graft inlet.

Computer Simulation↗
PubMed2000

Bactericidal properties of ozone and its potential application as a terminal disinfectant.

The efficacy of ozone as a terminal disinfectant was evaluated under laboratory conditions. Different microorganisms of importance to the food industry were inoculated onto stainless steel squares and incubated at various temperatures and relative humidities for up to 4 h. Survival of microorganisms from these controls was compared with identically incubated squares exposed to ozone. Exposure of the contaminated surfaces to ozone (2 ppm for 4 h) resulted in a reduction in microbial viability that ranged, depending on organism type, from 7.56 to 2.41 log values. For all the microorganisms tested, this loss in viability was significantly greater (P < 0.05) than that observed in the absence of ozone. Gram-negative bacteria were more sensitive to ozone than gram-positive organisms; bacteria were more sensitive than the yeast strain tested. Exposure to ozone (2 ppm for 4 h) in the presence of ultra-high temperature (UHT) milk resulted in a reduction in bacterial viability that ranged from 5.64 to 1.65 log values. In most cases, this reduction was significantly less (P < 0.05) than that achieved in the absence of organic material, although still significantly greater (P < 0.05) than that observed in the absence of ozone. The presence of a meat-based broth reduced the effectiveness of ozone to a greater extent, although the number of surviving gram-negative organisms was still significantly less (P < 0.05) than in the absence of ozone. Less than 1 log unit of yeast cells was destroyed when exposed to ozone in the presence of UHT milk or meat-based broth. Results of this investigation suggest that if applied after adequate cleaning ozone could be used as an effective disinfectant.

Animals↗
PubMed1998

Clinical relevance of in vitro propagation of activated lymphocytes from endomyocardial biopsy samples of pediatric heart transplant recipients.

In vivo activated T-lymphocytes can be cultured from endomyocardial biopsy samples of human cardiac allografts, sometimes even in the absence of histological rejection. We investigated the clinical relevance of this "lymphocyte growth assay" in pediatric heart transplant recipients. Specifically, we wished to determine if: (i) positive lymphocyte growth from EMB samples in the absence of significant rejection identifies a patient as being at increased risk for the development of acute rejection; (ii) withdrawal or major dose reduction of corticosteroids in the presence of lymphocyte growth results in high risk of rebound rejection; and (iii) presence of lymphocyte growth during acute rejection helps predict the response to treatment. Cultures were performed on 789 consecutive EMB samples from 65 pediatric heart transplant recipients in media containing 30 U/ml of recombinant IL-2. T-lymphocytes were cultured from 16% of EMB samples with low grade rejection (grade 0-1b) and from 34% of EMB samples with grade 2-4 rejection. EMB samples obtained early post-transplant (<180 days) were significantly more likely to yield positive lymphocyte growth compared to biopsies obtained late for any given rejection grade. Lymphocyte growth was comparable between patients managed with cyclosporine or tacrolimus based immunosuppression. For 227 EMB samples without rejection, a subsequent EMB sample was obtained within 12 weeks. Lymphocyte cultures were positive in 47 of these 227 EMB samples (21%), and in 19 out of 47 (40%) cases acute rejection (grade 2-4) was present on the follow-up EMB sample. By contrast, of 180 biopsies without growth, only 29 (16%) showed rejection at the next EMB (p<0.0001). When a follow-up biopsy was performed within 12 weeks of corticosteroid withdrawal, "rebound rejection" was observed in 3 out of 10 (30%) cases where the previous EMB sample yielded positive lymphocyte growth and in 4 out of 38 (11%) cases when it did not (p=0.29). The presence of lymphocyte growth in association with rejection was also predictive of whether rejection would resolve following high dose intravenous corticosteroid therapy (persistent rejection in 33 out of 50 (66%) cases with positive growth, versus 25 out of 80 (31%) cases without growth (p<0.0001)). Thus, positive lymphocyte growth is strongly associated with higher grade of rejection and earlier time from transplantation. Lymphocyte growth in the absence of rejection indicates high risk for rejection within the next 12 weeks. Growth in association with acute rejection indicates high probability of persistence of rejection following treatment with high dose corticosteroids.

Adolescent↗
PubMed1996

A 50-year perspective upon selective gastric vagotomy.

BACKGROUND: The occurrence of postvagotomy complications was initially considered an unavoidable but acceptable consequence of duodenal ulcer surgery. Following the description of "selective" vagotomy procedures, however, it became apparent that effective ulcer surgery might be accomplished without unpleasant sequellae. METHODS: In 1957 the experimental basis for "highly" selective vagotomy (HSV), which preserved antral innervation, was reported. HSV was performed in several European centers between 1960 and 1968, and was widely accepted there. Surgeons in the United States, in contrast, were largely reluctant to use HSV, an operation which had an excessive ulcer recurrence rate compared to vagotomy-antrectomy. More recently, HSV is recognized as a successful operation, due to more complete division of preganglionic gastric vagal nerves ("extended" HSV) and the liberal use of pyloric reconstruction in patients with juxtapyloric ulcers. RESULTS: HSV is performed with minimal morbidity, with an incidence of recurrent ulcer which is less than 5%. Complications such as dumping, diarrhea, and gastric atony are quite rare. CONCLUSIONS: HSV is an ideal procedure for most patients with duodenal ulcer. Because most operations for ulcer are performed for urgent or life-threatening problems, the most common operation performed in the United States today is truncal vagotomy combined with pyloroplasty or gastric resection. Earlier operation for chronic ulcer has many potential advantages.

Duodenal Ulcer↗
PubMed1996

Tumour bed biopsy detects the presence of multifocal disease in patients undergoing breast conservation therapy for primary breast carcinoma.

This study prospectively examined tumour bed biopsies in 135 consecutive patients undergoing conservative surgery for breast carcinoma. All had wide resection of the primary tumour and histologically clear margins. Twelve patients (9%) had positive tumour bed biopsies. Two subgroups of patients had positive bed biopsies; those with ductal carcinoma in situ, and a second group with more aggressive disease characterized by lymph node involvement, vascular invasion and a higher grade and mitotic count. As the majority of recurrences from breast carcinoma occur in the region of the primary tumour, bed biopsy may aid in the identification of a group of patients with multifocal or aggressive disease who are at increased risk of local recurrence.

Biopsy↗
PubMed1995

Collision of comet Shoemaker-Levy 9 with Jupiter observed by the NASA infrared telescope facility.

The National Aeronautics and Space Administration (NASA) Infrared Telescope Facility was used to investigate the collision of comet Shoemaker-Levy 9 with Jupiter from 12 July to 7 August 1994. Strong thermal infrared emission lasting several minutes was observed after the impacts of fragments C, G, and R. All impacts warmed the stratosphere and some the troposphere up to several degrees. The abundance of stratospheric ammonia increased by more than 50 times. Impact-related particles extended up to a level where the atmospheric pressure measured several millibars. The north polar near-infrared aurora brightened by nearly a factor of 5 a week after the impacts.

Ammonia↗
PubMed1995

The structured clinical instruction module: a novel strategy for improving the instruction of clinical skills.

We have previously shown that both medical students and residents demonstrate numerous important deficits when evaluating patients with abdominal complaints. To address these deficits, we implemented a pilot instructional program derived from the Objective Structured Clinical Examination. Fifty third-year medical students were presented with a 1-hr Structured Clinical Instruction Module (SCIM) of five stations, each station addressing a different aspect of the surgical evaluation of the abdomen. Simulated patients were present at two of the stations. Faculty from appropriate disciplines were present at the stations to provide standardized instruction according to predetermined curricular objectives. The medical students evaluated the SCIM for its specific characteristics, and they evaluated each of the five stations for its efficacy in increasing their clinical skills. All the specific aspects of the SCIM were given a rating significantly higher than neutral (P < 0.0001). Students agreed most strongly that the faculty were well prepared for the SCIM and that the faculty were enthusiastic. All of the SCIM stations were given a rating significantly higher than average (P < 0.0001). When compared to a conventional workshop, the SCIM scored significantly higher on all three common evaluation items. The SCIM was very well received by medical students as a format for clinical instruction. This unique modification of the Objective Structured Clinical Examination has potential for teaching important clinical skills that are not consistently mastered within current surgical curricula.

Adult↗
PubMed1983

Human spleen cells mediating natural killing: altered natural cytotoxicity of spleen effector cells from patients with carcinoma.

Spleen cells from eight patients with abdominal carcinoma and six patients undergoing major surgery for a variety of disease entities were assayed for natural cytotoxicity towards 51Cr-labelled K 562 target cells. Patients with abdominal cancer were shown to have relatively weak splenic natural cytotoxicity compared with the reactivity of effector cells from non-carcinoma patients. Nylon wool non-adherent spleen effector cells from cancer patients showed reduced cytolytic capacity compared with effector cells prepared from the spleens of other patients or peripheral blood mononuclear cells (PBMC) obtained from healthy individuals, whereas the splenic reactivity of non-cancer patients showed the same nylon wool separation profile as PBMC, high cytolytic activity being associated with nylon wool non-adherent effector cells. Splenic effector cell cytotoxicity from cancer and non-cancer patients was enhanced following exposure to human interferon, and inhibited by treatment with cholera toxin and simple sugars. Furthermore, fractionation of spleen cells on Percoll discontinuous density gradients demonstrated natural cytotoxic activity to reside predominantly in the low density cell fractions, similar to that found with NK cells from peripheral blood. Thus the properties described here for human cytotoxic spleen cells are similar to those described for peripheral blood NK cells, suggesting these two effector cell populations to be closely related, if not identical.

Adult↗
PubMed1983

Bupropion: clinical assay for amphetamine-like abuse potential.

Bupropion hydrochloride (100, 200, and 400 mg), d-amphetamine sulfate (15 and 30 mg), and placebo were compared in 13 volunteers who had histories of amphetamine abuse. Each dose was given orally at intervals of 3 or more days according to a double-blind, randomized crossover design. Bupropion had little or no effect on blood pressure, pulse rate, respiration, body temperature, pupil diameter, subjective appetite, food intake, sleep, or selected subscales of the Addiction Research Center Inventory and Single Dose Questionnaire. Conversely, d-amphetamine was active on most measures. It is concluded that, despite bupropion's reinforcing properties in animals, the compound is not amphetamine-like and is unlikely to give rise to such abuse in humans.

Adult↗