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Biomedical subjects

R Fitzgerald

Publications and source records attributed to R Fitzgerald.

At least 55 records · Page 3Linked to original sources
PubMed1989

Evaluation of chlordecone in a two-stage model of hepatocarcinogenesis: a significant sex difference in the hepatocellular carcinoma incidence.

Chlordecone (Kepone) has been extensively studied for its toxicity in male production workers who were exposed to large quantities of this organochlorine pesticide. Concern that these workers might be at an increased risk of developing liver cancer prompted us to test chlordecone in a two-stage rat model of hepatocarcinogenesis. Chlordecone acted largely as a liver tumor promoter rather than as a complete hepatic carcinogen in both male and female Sprague-Dawley rats. Dose-response experiments showed that the hepatocarcinogenic effects of long-term chlordecone administration became undetectable at concentrations in non-initiated rat liver in the same range as those measured in human biopsies taken from exposed workers who exhibited no liver effects. Although the toxicity of chlordecone in women has never been studied, we found a dramatic sex difference in the incidence of malignant liver tumors caused by chlordecone promotion in rats. Frank hepatocellular carcinomas were observed in up to 63% of female rats whose livers were previously 'initiated' with a subcarcinogenic dose of diethylnitrosamine given 24 h after partial hepatectomy, and then 'promoted' by 27 weeks of chlordecone administration. In contrast, none of comparably treated males had malignant liver tumors, even after 44 weeks of 'promotion' with chlordecone. Females in the diethylnitrosamine-initiated/chlordecone-promotion groups also contained gamma-glutamyltranspeptidase-positive 'preneoplastic' hepatocellular foci that were more abundant and larger than those observed in comparably-treated males. Moreover, because similar levels of chlordecone were measured in the livers of both sexes at the end of the experimental period, the development of hepatocellular carcinomas in the diethylnitrosamine-initiated female rats appeared to be due to their increased sensitivity to the promotion treatment.

Animals↗
PubMed1988

The value of routine CSF analysis during lumbar radiculography for low back pain.

The medical notes of 370 orthopaedic patients with low back pain, who underwent lumbar radiculography, were retrospectively reviewed to determine the effect, if any, that CSF analysis had on their subsequent management. It was found that no apparent alteration of management occurred in a single patient and hence the routine sampling of CSF during lumbar radiculography for uncomplicated low back pain has been discontinued in our department.

Back Pain↗
PubMed1988

Stress changes of the wrist in adolescent gymnasts.

The radiographic appearances are reported of chronic stress to the wrist joints of eight adolescent males, seven gymnasts and one roller skater. These consist of bilateral, asymmetrical widening and irregularity of the distal radial growth plates with an ill-defined cystic appearance, sclerosis and flaring of the metaphyses in all eight cases. Similar but less marked changes were present in the distal ulnar growth plates in five cases. The aetiology is thought to be that of a Salter Type I stress fracture of the growth plate due to chronic repetitive shear forces applied to the hyperextended wrist joint. Rapid healing of the stress fracture will occur with cessation of the sporting activity but continued strenuous use of the wrists will result in further widening and irregularity of the growth plate. The differential diagnosis of the radiographic appearances and previous literature are discussed.

Adolescent↗
PubMed1985

Arterial CO2 partial pressure affects diaphragmatic function.

The purpose of this study was to examine in an in vivo preparation acute variations of PCO2 on diaphragmatic contractility. Plaster casts were snugly fit around the abdomen of six open-chested dogs, moving the abdominal contents rostrally. Diaphragmatic contractions against this very fixed load in response to phrenic nerve stimulation (supramaximal voltage at 1, 20, 50, and 80 Hz) or during spontaneous inspiratory efforts were virtually isometric (quasi-isometric). Transdiaphragmatic pressure (Pdi) measured by an abdominal balloon was used as an index of diaphragmatic contractility. Arterial PCO2 (PaCO2) was reduced by hyperventilation and raised by increasing PICO2. Pdi values in response to stimulation at 1, 20, 50, and 80 Hz in ranges I (PaCO2 = 0-19 Torr) and II (PaCO2 = 20-34 Torr) did not differ statistically from the control Pdi values (range III; PaCO2 = 35-45 Torr). In range IV (PaCO2 = 46-70 Torr) Pdi values for stimulations of 20, 50, and 80 Hz were significantly lower than control. In range V (PaCO2 = 71-90 Torr), VI (PaCO2 = 91-101 Torr), and VII (PaCO2 greater than or equal to 102 Torr) Pdi values were significantly less than those in range IV at all frequencies of stimulation. In the four dogs measured during spontaneous inspiratory efforts the integrated diaphragmatic electromyogram (Edi) was correlated with the Pdi. As PaCO2 rose (range III to VII), the Pdi values observed at 25, 50, 75, 100% of the maximum Edi (of range III) were significantly lower than the Pdi value of range III.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkalosis, Respiratory↗
PubMed1984

An operative technique to reduce valve colonisation.

Using a multiple skin preparation technique, drape edges soaked in chlorhexidine and valves primed with gentamicin solution CSF shunt (VP) colonisation rate has been reduced to 2.4% of 82 operations.

C-Reactive Protein↗
PubMed1983

Meconium thorax.

A case of meconium thorax resulting from spontaneous perforation of the colon associated with a right Bochdalek's foramen, without herniation, is presented. The baby had immediate respiratory distress postpartum resulting from the meconium in the pleural cavity. No fetal distress was detected, in spite of electrode monitoring in labor, to account for the colonic perforation.

Colonic Diseases↗
PubMed1976

The health of clients of a social service department.

A survey was undertaken of the health problems and current medical care of new clients making contact with the Social Service Department of an outer London borough. The findings indicated that social-service clients represent a high-morbidity group of the population: 47 per cent of the survey sample showed evidence of major physical illness or disability, and 16 per cent of major mental illness. A sub-group was identified, corresponding to about 300 new clients annually, who suffered from serious ill-health or disability, but were at the time not under medical care.These findings support the argument for closer liaison between medical and social services in the community and, in particular, for more social-worker attachments in general practice.

Adolescent↗
PubMed1968

Solid-state energy-dispersion spectrometer for electron-microprobe x-ray analysis.

Improved lithium-drifted silicon solid-state detectors allow detection and energy dispersion of x-rays of about 3 to 30 kiloelectron volts in the electron-microprobe x-ray analyzer. Energy resolution is sufficient to separate peaks of characteristic x-rays of elements adjacent in the periodic system at atomic number 20 and higher. The detected x-ray spectrum emitted from an unknown sample can be recorded with a multichannel analyzer in approximately 60 seconds.

Electron Probe Microanalysis↗
PubMedDate not supplied

Effects of the holmium:YAG and erbium:YAG lasers on endotracheal tubes.

Endotracheal tube (ET) fire is the most frequent complication arising with laser surgery in the upper aerodigestive tract. No data are available about the safety of commonly used ETs when used with recently developed high-energy pulsed lasers, working with only a minimal thermal component but mainly photoablative. A comparative in vitro study was performed with three types of endotracheal tubes to assess their resistance to wall and cuff damage by the laser beams of two pulsed infrared solid-state lasers. ET perforation was attempted with the erbium:YAG (lambda = 2,930 nm) and holmium:YAG (lambda = 2,120 nm) lasers. For all experiments, a repetition rate of 5 Hz was used. The 2.5-microseconds holmium:YAG pulses were coupled into a nylon fibre of 400 microns diameter. The 2.0-microseconds erbium:YAG laser pulses were applied to ETs through a lens system providing a spot size diameter of 200 microns. Polyvinyl chloride and silicon ET segments were exposed to laser pulse energies from 97 to 500 mJ in the presence of different anaesthetic gas mixtures. The time from the onset of exposure to tube perforation was recorded. Thermal gradients following laser application were measured. Laser exposure was continued for up to 90 s, unless tube ignition occurred. At all energy levels tested, the photo-ablative mechanism of laser-tube interaction, with few thermal components, led to laser-induced tube ignition if an FiO2 > 21% for the holmium:YAG and 34% for the erbium:YAG laser was established. With increasing pulse energies, ET segments ignited sooner. MLT tubes performed best in the present safety test.

Aluminum Silicates↗