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Biomedical subjects

J Clegg

Publications and source records attributed to J Clegg.

34 records · Page 2Linked to original sources
PubMed1997

Embryos of Artemia franciscana survive four years of continuous anoxia: the case for complete metabolic rate depression

Encysted gastrula embryos of the crustacean Artemia franciscana have acquired an array of adaptations that enable them to survive a wide variety of environmental extremes.The present paper shows that at least 60 % survive 4 years of continuous anoxia at physiological temperatures (20­23 °C) when fully hydrated. Although these embryos appear to carry on a metabolism during the first day of anoxia, no evidence for a continuing metabolism throughout the subsequent 4 years was obtained. During this period, there were no measurable changes in the levels of their stored, mobilizable carbohydrates (trehalose, glycogen, glycerol). Calculations indicate that, if these carbohydrates are being utilized at all during anoxia, the rate is at the least 50 000 times lower than the aerobic rate (lower limit of detection). Indications of proteolysis during prolonged anoxia were sought but not found. Under starvation conditions, the life span of larvae produced from embryos that had undergone 4 years of anoxia was not significantly different from that of larvae produced by embryos that had not experienced anoxia. Thus, all substrates and other metabolites required to support embryonic development to the nauplius, as well as endogenous (unfed) larval growth and molting, are retained during 4 years of anoxia. It is not possible to prove experimentally the absence of a metabolic rate in anoxic embryos under physiological conditions of hydration and temperature. Nevertheless, on the basis of the results presented here, I will make the case that the anoxic embryo brings its metabolism to a reversible standstill. Such a conclusion requires that these embryos maintain their structural integrity in the absence of measurable biosynthesis and free energy flow and are thus an exception to a major biological generality. Potential mechanisms involved in their stability are discussed.

Journal Article↗
PubMed1997

Effect of anaerobiosis on cysteine protease regulation during the embryonic-larval transition in

Hydrated encysted embryos of the brine shrimp Artemia franciscana have the ability to withstand years in anaerobic sea water using metabolic strategies that enable them to inactivate all cell metabolic activities and then to resume development when placed in aerobic sea water. However, this unique characteristic of Artemia franciscana embryos is lost during a very short period, at the embryonic­larval transition period of development, coincident with the appearance of prenauplius larvae. Thus, while encysted embryos show complete inhibition of proteolysis over at least 4 years under anoxia, control of this activity, together with resistance to anoxia, is lost in newly hatched nauplius larvae after only a few days in anaerobic sea water. In contrast to encysted embryos, young larvae in anaerobic sea water produce large amounts of lactic acid, which reaches a concentration of nearly 50 mmol l-1 within 12 h of incubation. The accumulated lactic acid is believed to reduce the intracellular pH (pHi) to considerably less than 6.3, the value found in encysted embryos after 5 months in anaerobic sea water. We find that larvae, in contrast to embryos, lose cytoplasmic proteins at the rate of 4­5 ng h-1 larva-1 upon transfer to anaerobic sea water, while yolk proteins are not degraded in either embryos or larvae under anoxic conditions. The decline in cytoplasmic protein levels in anaerobic larvae may be due to activation of an endogenous cysteine protease (CP) as the pHi becomes acidic. Contributing to the apparent uncontrolled CP activity is a decrease in the level of cysteine protease inhibitor (CPI) activity during the embryonic­larval transition period, resulting in an increase in the CP/CPI ratio, from approximately 0.5 in embryos to greater than 1.0 in newly hatched larvae. Finally, data are presented to suggest that loss of the 26 kDa stress protein from embryos during the embryonic­larval transition may also contribute to the loss in resistance of young nauplius larvae of A. franciscana to anaerobic conditions.

Journal Article↗
PubMed1994

Routine ultrasound screening for neonatal hip instability. Can it abolish late-presenting congenital dislocation of the hip?

We have undertaken routine ultrasound screening for neonatal hip instability in Coventry since June 1989. Of the 14,050 babies scanned during the first three years, 847 (6%) had ultrasound abnormalities. A grading system, based on the percentage of femoral head coverage, is presented. The proportion of abnormal hips decreased gradually so that by nine weeks, 90% had normal ultrasound appearances. Abnormality was more common in babies with a family history of CDH and in breech presentations. All babies with clinically abnormal hips had an abnormal first ultrasound examination. Five babies not diagnosed by clinical examination and with no risk factors had abnormal ultrasound appearances and were subsequently found to have clinically abnormal hips. Routine ultrasound screening has detected cases which would otherwise have presented late.

Female↗
PubMed1989

A simple method of identifying loosening or infection of hip prostheses in nuclear medicine.

Joint replacement is now established as a reliable orthopaedic procedure for the relief of many painful degenerative conditions of the hip. When successful it enhances hip movement and relieves pain with a concomitant improvement in function and well being for the patient. When unsuccessful the persistence of pain usually signifies loosening or infection. Loosening may result from mechanical failure or infection. Accurate distinction between septic and aseptic loosening is important for planning and executing surgical intervention. The experience of the Department of Nuclear Medicine in Coventry assessing pathology in painful hip prostheses was retrospectively reviewed in 47 patients. These patients were imaged from 1985 to 1987 and all had good clinical follow-up enabling the diagnosis of loosening, infection or normal to be made with confidence. All patients had three phase bone imaging and some had additional gallium imaging. The images were reviewed with particular emphasis on the pattern of uptake in the late bone image and congruence of abnormal uptake in the early bone image and gallium image. It is concluded that for the majority of patients simple three phase bone imaging will provide the required diagnostic information.

Aged↗
PubMed1989

Ultrasound screening of hips at risk for CDH. Failure to reduce the incidence of late cases.

Of 4,617 babies born in Coventry in 1986, a total of 448 (9.7%) had either clinical abnormality of the hip or at risk factors for CDH. All were examined by ultrasound, but only 17 required treatment (3.7 per 1,000); in five of these no clinical abnormality had been detected. An additional 81 babies had ultrasound abnormalities but did not require treatment, despite the fact that ultrasound at first showed major hip displacement in 17 of them. Three late cases of CDH have presented among the babies born in 1986, but not examined by ultrasound. This incidence of late CDH is unchanged compared with the previous nine years, although ultrasound had detected covert displacement in a number of hips.

Hip Dislocation, Congenital↗
PubMed1984

Changes in developmental capacity of artemia cyst and chromosomal aberrations in lettuce seeds flown aboard Salyut-7 (Biobloc III experiment).

This paper gives the results of investigations performed on the first container (A) of the Biobloc III experiment, flown aboard the orbital station Salyut 7 for 40 days. The space flight resulted in a decreased developmental capacity of Arterlia cysts, hit or not hit by the HZE particles. No effect was observed in cysts in bulk. A synergetic effect of microgravity and gamma pre irradiation is described. The germination of in-flight lettuce seeds was decreased. The space flight resulted also in a higher percentage of cells with chromosomal aberrations. Relations between biological response, TEL and location of HZE particles are discussed.

Animals↗
PubMed1983

Results on Artemia cysts, lettuce and tobacco seeds in the Biobloc 4 experiment flown aboard the Soviet Biosatellite Cosmos 1129.

Artemia cysts, lettuce and tobacco seeds were flown aboard the Cosmos 1129 for 19 days. A correlative method was used in order to determine the passage of cosmic heavy ions (HZE particles) through the biological test objects. This space flight resulted in a decrease on hatchability, nucleic acid and protein synthesis in hydrated Artemia cysts. HZE particle effects on plant cellular chromosomes are confirmed. In tobacco seeds, a stimulating effect on germination rate and a higher frequency of abnormalities were observed. Dormant biological objects are a very suitable material to study cosmic ray effects: these objects can be arranged in monolayers and sandwiched between visual track detectors in order to determine the passage of the cosmic heavy ions (HZE particles). On the other hand this method allows us to study effects of microgravity and those of the protonic component of cosmic rays in the objects not hit by the HZE articles.

Animals↗
PubMed1977

The results of the pseudarthrosis after removal of an infected total hip prosthesis.

Twenty-nine patients with thirty pseudarthroses after removal of infected total hip prostheses have been reviewed one to six years later. Six hips still had a discharging sinus. Complete removal of all cement was found to be essential for healing, and various points in the technique of its clearance have been made. In this respect radio-opaque cement was a great advantage, and lateral guttering of the femur was most effective. Compared with the situation before replacement considerable relief of pain was obtained in most patients but there was much less improvement in function.

Activities of Daily Living↗
PubMedDate not supplied

Intraoperative wedging of casts: correction of residual angulation after manipulation.

Seventy children, aged 2-14 years, had a manipulation under anaesthetic (MUA) of a forearm or lower leg fracture, in which the MUA failed to fully correct the deformity in 16. An opening wedge (WEDGE) was performed while still under the original anaesthetic in one group and compared to a parallel but uncontrolled group using the traditional regimen of remanipulation (RE-MUA). There was an observed reduction in the average time under anaesthetic comparing WEDGE to RE-MUA in the forearms (34 vs. 46 min) and in the legs (42 vs. 61 min). There was no obvious difference between the proportion of those needing "further adjustments" (defined as wedging at outpatients or a further MUA) if the fracture displaced comparing WEDGING (zero of six) to RE-MUA (one of 10), and there was also no obvious increased time to union. At review, there was < 10 degrees malunion in any plane, which should not predispose to restricted forearm rotation or chronic ligamentous strain/joint degeneration in the leg.

Adolescent↗
PubMedDate not supplied

Variation of Baumann's angle with age, sex, and side: implications for its use in radiological monitoring of supracondylar fracture of the humerus in children.

We examined 577 elbow radiographs of children aged 2-14 years attending an accident and emergency department prospectively over a 2-year period, and after excluding 7% with an effusion, fracture, or oblique view, we calculated Baumann's angle on the remainder. We grouped the radiographs by age, sex, and side, giving 52 groups with a minimum of 10 radiographs in each group. Baumann's angle was found to range from 64-82 degrees, mean 73.6 +/- 2 SD = 8.73 in boys; 69-81, mean 75.6 +/- 2 SD = 5.78 in girls; 64-82, mean 73.5 +/- 2 SD = 5.78 on the left; and 66-82, mean 73.7 +/- 2 SD = 7.47 on the right. Analysis of variance showed there was no significant difference in the mean comparing boys with girls at each age, left to right at each age in the boys or girls, and there was no increasing or decreasing trend over the years in either sex on each side.

Adolescent↗
PubMedDate not supplied

Perthes' disease after "irritable hip": delayed bone age shows the hip is a "marked man".

We report 13 children, aged 4 through 8 years, who were seen with a prolonged or recurrent irritable hip syndrome. Only those with > 2 years' delay in their bone age eventually declared themselves to have been in the early phase of Perthes' disease at initial examination when the original hip radiographs had been normal. A plain wrist radiograph was found to be a useful screening tool to differentiate those who should have early repeat investigation such as radiographs, or preferably a magnetic resonance image scan if available, to detect the disease in its initial phase. This facilitated early regular imaging to assess femoral head shape and so permitted early treatment before deformity had occurred in those with whole-head involvement.

Age Determination by Skeleton↗
PubMedDate not supplied

Evaluating blood loss in children's orthopaedic surgery: a simplified method of photometric analysis of eluted swabs.

Assessment of intraoperative blood loss by the traditional method of weighing swabs (4 x 4-in. gauze) is propounded to estimate approximately 75% of total loss, although many believe this still underestimates actual loss. The various components of this technique were studied by using the method of colorimetric analysis of eluted swabs, but utilising a modern spectrophotometer. We modified and simplified the technique, resulting in > 95% accuracy in all instances, and by so doing, created a potential technique for use in children's orthopaedic surgery. Weighing swabs was found to estimate only approximately 50% of total loss, and this was supported in the pilot clinical study by a postoperative decrease in haemoglobin of 8-17%, despite transfusion, when transfusion was based on the traditional "75%" rule. Because it is impractical to elute theatre apparel and instruments to increase the accuracy of the elution method in the perioperative time scale necessary, a compromise may be to use the new "50%" rule as a better estimate of total blood loss when calculating transfusion requirements.

Blood Loss, Surgical↗