Biomedical subjects
Publications and source records attributed to G Jones.
Cortocosteroids have profound effects on bone, leading to accelerated osteoporosis and fracture. This review will attempt to summarize current knowledge about their effects in light of new information and important remaining questions, especially with respect to treatment of this common condition.
Total parenteral nutrition (TPN)-induced hepatic steatosis is the most common complication of TPN administration to humans. The mechanism of TPN-induced hepatic steatosis has not been studied in young mammals. The goal of this study was to determine the mechanism of TPN-induced hepatic steatosis in the weanling rat and the effect of supplementation of TPN with choline and/or cysteine on TPN-induced hepatic steatosis. In the weanling rat, we investigated the effect of TPN administration on histologic hepatic steatosis, total hepatic lipid, hepatic acetyl-CoA-carboxylase (ACC--the rate limiting enzyme in fatty acid synthesis) specific activity, and total plasma lipids. TPN administration resulted in a threefold increase in hepatic lipid as compared with control and sham animals (TPN 138 +/- 12 mg/g liver versus control 57 +/- 1), an increase in histologic steatosis (TPN 3.7 versus control 1.3), and a decline in total plasma lipid (TPN 2.1 +/- 0.3 g/L versus control 4.1 +/- 0.3). TPN-induced hepatic steatosis in the weanling rat was not associated with an increase in ACC specific activity (TPN 2.10 +/- 0.33 nmol/min/mg protein versus control 2.85 +/- 0.23). Supplementation of the TPN with choline (15 mg/day) did not significantly lessen hepatic steatosis; however, supplementation of TPN with cysteine (2.5 mg/day) or with cysteine and choline did result in a significant lessening of hepatic lipid content and of histologic steatosis and a normalization of total plasma lipid.(ABSTRACT TRUNCATED AT 250 WORDS)
There has been an explosive interest in endoscopic techniques by plastic surgeons over the past two years. Procedures such as facial rejuvenation, breast augmentation and abdominoplasty are being performed with endoscopic assistance. Endoscopic operations require a complex setup with components such as video camera, light sources, cables and hard instruments. The Hopkins Rod Lens system consists of optical fibers for illumination, an objective lens, an image retrieval system, a series of rods and lenses, and an eyepiece for image collection. Good illumination of the body cavity is essential for endoscopic procedures. Placement of the video camera on the eyepiece of the endoscope gives a clear, brightly illuminated large image on the monitor. The video monitor provides the surgical team with the endoscopic image. It is important to become familiar with the equipment before actually doing cases. Several options exist for staff education. In the operating room the endoscopic cart needs to be positioned to allow a clear unrestricted view of the video monitor by the surgeon and the operating team. Fogging of the endoscope may be prevented during induction by using FREDD (a fog reduction/elimination device) or a warm bath. The camera needs to be white balanced. During the procedure, the nurse monitors the level of dissection and assesses for clogging of the suction.
Although plastic surgeons had been slow to incorporate endoscopic techniques into their surgical armamentarium, there has been considerable interest in this field during the last 2 years. The aim of endoscopic brow lifting has been to achieve elevation of the brow through small scalp incisions without the associated nerve damage of the open approach and to accurately address excision of the muscles responsible for frowning. Endoscopic neck lift is a more recently pioneered technique which, although still in developmental stages, appears to provide good results. The technique involves undermining the skin of the neck extending from the chain to the jawline around the ear. Endoscopic facelifting is still very much in the experimental stages. Endoscopic techniques reduce the need for an incision in front of the ears. Using the endoscope, it has become a simple matter to perform a transaxillary breast augmentation using very small axillary incisions and precise placement of the implants. This results in excellent symmetry postoperatively and easy scar concealment. Abdominoplasty is another example of a procedure usually associated with a long incision and some degree of postoperative pain and immobility. Endoscopic abdominoplasty has been devised to provide not only contouring of abdominal fat through liposuction, but correction of the weakened abdominal muscle through a small incision placed just above the suprapubic hairline.
We have presented an alternative form of management for the difficult ear replant in which conventional venous outflow cannot be reestablished. Early and aggressive medicinal leeching provided an excellent means of venous decompression until neovascularization had taken place. The primary use of leeches in such small composite replants may be superior to the time-consuming and technically difficult exercise of trying to find and anastomose suitable veins. In selected patients this technique may allow successful replantation of the amputated ear, thereby providing a superior aesthetic result to most forms of secondary reconstruction.
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1. This paper describes the in vitro pharmacology of ZM 241385 (4-(2-[7-amino-2-(2-furyl) [1,2,4]-triazolo[2,3-a][1,3,5]triazin- 5-yl amino]ethyl) phenol), a novel non-xanthine adenosine receptor antagonist with selectivity for the A2a receptor subtype. 2. ZM 241385 had high affinity for A2a receptors. In rat phaeochromocytoma cell membranes, ZM 241385 displaced binding of tritiated 5'-N-ethylcarboxamidoadenosine (NECA) with a pIC50 of 9.52, (95% confidence limits, c.l., 9.02-10.02). In guinea-pig isolated Langendorff hearts, ZM 241385 antagonized vasodilatation of the coronary bed produced by 2-chloroadenosine (2-CADO) and 2-[p-(2-carboxyethyl) phenethylamino]-5'-N-ethylcarboxamidoadenosine (CGS21680) with pA2 values of 8.57 (c.l., 8.45-8.68) and 9.02 (c.l., 8.79-9.24) respectively. 3. ZM 241385 had low potency at A2b receptors and antagonized the relaxant effects of adenosine in the guinea-pig aorta with a pA2 of 7.06, (c.l., 6.92-7.19). 4. ZM 241385 had a low affinity at A1 receptors. In rat cerebral cortex membranes it displaced tritiated R-phenylisopropyladenosine (R-PIA) with a pIC50 of 5.69 (c.l., 5.57-5.81). ZM 241385 antagonized the bradycardic action of 2-CADO in guinea-pig atria with a pA2 of 5.95 (c.l., 5.72-6.18). 5. ZM 241385 had low affinity for A3 receptors. At cloned rat A3 receptors expressed in chinese hamster ovary cells, it displaced iodinated aminobenzyl-5'-N-methylcarboxamido adenosine (AB-MECA) with a pIC50 of 3.82 (c.l., 3.67-4.06). 6. ZM 241385 had no significant additional pharmacological effects on the isolated tissues used in these studies at concentrations three orders of magnitude greater than those which block A2a receptors. At 10 microM it displayed only minor inhibition of the bradycardic effects in guinea-pig atria to some concentrations of carbachol. At 10 microM, ZM 241385 had a small inhibitory effect on relaxant effects of isoprenaline in guinea-pig aortae but no effect on sodium nitrite-induced relaxation. ZM 241385(100 microM) was without effect on phenylephrine-induced tone in guinea-pig aortae.7. ZM 241385 (10 microM) had no inhibitory effect on rat hepatocyte phosphodiesterase types I, II, III and IV but caused a small inhibition of the calcium calmodulin-activated type I enzyme.8. ZM 241385 is the most selective adenosine A2a receptor antagonist yet described and is therefore a useful tool for characterization of responses mediated by A2 adenosine receptors.
This paper provides a critical overview of developments and issues in competitive anxiety research. The discussion is divided into sections dealing with general arousal-based approaches, general anxiety-based approaches and, finally, multi-dimensional anxiety-based approaches. The major emphasis is on multidimensional anxiety-based approaches, in which a number of factors and issues surrounding the competitive anxiety response are addressed, including: conceptual and measurement developments; antecedents of competitive anxiety; temporal patterning of the response; and frequency of competition-related cognitive intrusions. Research which has examined the relationship between multidimensional anxiety and performance is considered in detail, including debilitative and facilitative competitive anxiety states and catastrophe models. A control model of debilitative and facilitative competitive anxiety is proposed. Finally, recommendations for future research are suggested.
Determination of the molecular modes of action of juvenile hormone to regulate gene expression has remained an elusive goal. This review discusses how studies on JH action have been influenced by the perspectives based on the mode of action of vertebrate retinoid/steroid hormones. Also identified are assumptions implicit in the experimental approaches used thus far, as well as alternative perspectives from which to frame future hypotheses on JH action.
The risk of osteoporotic fracture is related to peak bone mass achieved at skeletal maturity and subsequent bone loss. Although premature menopause is a risk factor for osteoporosis, the effect of exposure to endogenous estrogen during a woman's reproductive years is poorly characterized. We analyzed the relationship between reproductive factors and estrogen exposure on bone mineral density (BMD) and incidence of atraumatic fracture in data from 1091 women (age: 70 +/- 7.2 yr; mean +/- SD) participating in the Dubbo Osteoporosis Epidemiology Study. Age- and weight-adjusted BMD among women who had used estrogen replacement therapy (ERT) for more than 5 yr was higher at the lumbar spine and femoral neck by 13.7% and 10.2% (P < 0.001), respectively, compared with women who had used ERT for less than 5 yr or nonusers. Duration of exposure to estrogen (years of menstruation plus postmenopausal ERT use) was associated with higher BMD, such that BMD increased by 2-3% for every 10-yr increase in years of estrogen exposure; thus women who menstruated for more than 40 yr had a 6-8% higher BMD than did women who menstruated for less than 30 yr. Higher BMD was also significantly associated with high parity, such that nulliparous women had 5-6% lower BMD than did their peers of the same age and weight. The incidence of atraumatic fractures among non-ERT users was higher than that of ERT-users [odds ratio (OR): 1.06; 95% confidence interval (CI): 0.94-1.16] and was significantly lower among parous women than among nulliparous women (OR 0.94; 95% CI: 0.84-0.98) in univariate analysis. Longer duration of menstruation was associated with lower fracture incidence (OR for 1 SD = 6.6 yr: 0.93; 95% CI: 0.86-1.02). Moreover, when all of these factors were considered simultaneously, parity remained a significant determinant of fracture as well as femoral neck BMD. We conclude that high parity and longer duration of exposure to estrogen, either through natural menstruation or postmenopausal ERT, have protective effects on BMD and are associated with a reduced incidence of atraumatic fracture in a population-based study.
Echolocation call intensity was measured in the laboratory for five species of British insectivorous bats in free flight and in the hand. All species showed similar call intensities of between 80 and 90 dB peSPL (peak equivalent SPL) at 1 m during flight except Plecotus auritus, whose call intensity was between 68 and 77 dB peSPL at 1 m. Calls from stationary bats were about 13 dB less intense than calls during flight. A method is proposed to measure the root mean square (rms) amplitude of echolocation calls and, hence, to calculate the energy flux density of the call. The constant-frequency calls of Rhinolophus hipposideros have energy flux densities approximately ten times higher than those of bats using frequency-modulated calls as a result of their longer durations and lower crest factors. It is argued that the low-intensity calls of P. auritus allow it to approach tympanate moths more closely before triggering their escape response.
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OBJECTIVE: Osteoarthritis (OA) is associated with an increase in bone density both locally and at distant sites. Prospective data are limited on the relationship between OA and fracture. We studied the possible relationship between self-reported OA, bone density, postural stability measures, and atraumatic fractures as part of a study of men and women over 60 years of age. METHODS: Subjects were part of the Dubbo Osteoporosis Epidemiology Study (a longitudinal population based study of fracture risk factors). Bone density was measured by dual energy x-ray absorptiometry. Postural stability was assessed by the validated measures of quadriceps strength and sway. Medication use and self-reported arthritis were assessed by a structured personal interview. Fractures were ascertained retrospectively by interview and prospectively by viewing radiographic reports for fracture. RESULTS: Among a study population of 1101 women and 720 men (mean age 69) there were 462 subjects (25%) who reported a diagnosis of OA. In both sexes, subjects with OA had higher bone density (adjusted for age and body mass index) at both the femoral neck (men, p = 0.026; women, p = 0.048) and lumbar spine (men, p = 0.0007; women, p = 0.0007). However, in both sexes, those with self-reported OA also had higher body sway and lower quadriceps strength. The combination of these observed differences in fracture risk factors led to no predicted change in fracture risk overall when using established nomograms for this population [men, OR = 1.11 (95% CI 0.83-1.45); women, OR = 1.08 (95% CI 0.83-1.39)]. This paralleled our observational finding that self-reported OA was not associated with a decrease in fracture incidence compared to those not reporting OA in both men (RR 0.64, 95% CI 0.29-1.39) and women (RR 1.00, 95% CI 0.66-1.51). CONCLUSION: Individuals with self-reported OA, despite higher bone density, are not protected against nonvertebral osteoporotic fracture, apparently due to worsened postural stability and thus an increased tendency to fall.
OBJECTIVE: To describe the relationship between spinal degenerative disease and bone density in the elderly both cross sectionally and longitudinally. METHODS: Random population based sample of 113 men and 187 women over 60 yrs of age participating in the Dubbo Osteoporosis Epidemiology Study (a longitudinal population based study of fracture risk factors) who had bone density measured on 2 occasions (average interval 2.5 yrs) and spinal radiographs on one occasion (performed according to a standardized approach). RESULTS: Spinal degenerative disease, of varying severity, was common in this population (osteophytes 69%, disc narrowing 67%, posterior element disease 99%). Scores for osteophytosis, disc narrowing, and posterior element disease (together with age and body mass index) independently explained 43% of the variation in spinal bone density in men (p < 0.00001) and 26% in women (p < 0.00001). The rate of change at the spine increased with increasing severity of osteophytosis in both men (p = 0.03) and women (p = 0.05), but not the other measures, and the total amount of variation explained by these measures was modest. In comparison, severity of spinal degenerative disease had only a modest but significant relationship with femoral neck bone density in both sexes, but not its rate of change. Subjects with any degree of osteophytosis had higher bone density compared to those without osteophytes at both the lumbar spine (men 21% higher, 95% CI 12-31; women 16% higher, 95% CI 9-23) and, to a lesser extent, femoral neck (men 12% higher, 95% CI 4-20; women 6% higher, 95% CI 1-13). Vascular calcification had no relationship with bone density at either spine or hip. CONCLUSION: Spinal bone density measurement and its sequential followup may be erroneous in the elderly due to concomitant degenerative disease. Bone density at the femoral neck was much less affected by spinal degenerative disease, which suggests that this site may be more efficacious for both monitoring response to treatment and determining fracture risk in the elderly.
The standard implementation of enzyme-linked immunosorbent assay (ELISA) for single analytes can lead to false conclusions if cross reacting compounds are present in the sample. This paper discusses the extension of the usual four-parameter logistic model for ELISA to the case of multiple cross-reacting analytes. The use of the extended model in multianalyte analysis (MELISA) is illustrated and compared with a more simplistic approach. Data on the analysis of a binary mixture of s-triazines suggests the superiority of the proposed model. This model is also suitable for other forms of immunoassay that use the four-parameter logistic curve.
A downward trend in the incidence of acquired rubella in England and Wales was reversed in 1993 when there were local outbreaks. These affected young adult males in particular, especially those living in college residences. Some spread to local antenatal populations occurred. Twenty-five confirmed infections were reported in pregnant women, most of whom were young and in their first pregnancy; this compares with totals of 12 and two in 1991 and 1992, respectively. Reports of congenital rubella have not risen since the 1993 outbreaks. Diagnosis lags behind birth, however, and further evaluation may be needed. Notifications of 14 infants, including one set of triplets, born with congenital infection since the beginning of 1991 have been received. Nine of the 12 mothers were immigrants, and three of these acquired their infection abroad. Data on antibody prevalence have revealed a large pool of susceptible males aged 10 to 25 years, which indicates that outbreaks in males would continue for some years if no action were taken. The national measles and rubella vaccination campaign in schools this month should abolish the difference in susceptibility between boys and girls up to 16 years of age and hasten progress towards the interruption of rubella transmission in the United Kingdom. Susceptibility in girls aged 13 to 14 years rose to 5.8% in 1993 from an average of 3.6% between 1986 and 1992. This suggests that the vaccination of schoolgirls has recently declined, but this component of the selective rubella vaccination programme will be discontinued after the measles and rubella campaign.(ABSTRACT TRUNCATED AT 250 WORDS)
OBJECTIVES: To determine prospectively the rates of change in bone mineral density in elderly people and to examine the relation between lifestyle and demographic factors and these rates of change. DESIGN: Longitudinal population based study. SETTING: Dubbo, New South Wales, Australia. SUBJECTS: Representative sample (n = 769) of residents aged > or = 60 on 1 January 1989. MAIN OUTCOME MEASURE: Rates of change in bone mineral density measured prospectively (mean scan interval 2.5 years) at the femoral neck and lumbar spine by dual energy x ray absorptiometry. RESULTS: Summary rates of loss in the femoral neck were 0.96% per year (95% confidence interval 0.64% to 1.28%) in women and 0.82% per year (0.52% to 1.12%) in men. Importantly, rates of loss at the femoral neck (both percentage and absolute) increased in both sexes with advancing age. No significant loss was evident in either sex at the lumbar spine, probably because of coexistent osteoarthritis. Lifestyle factors had only modest effects on rates of loss at either site. CONCLUSIONS: These data show that bone density of the femoral neck declines at an increasing rate in elderly people, and as this site is predictive of fracture suggest that treatment to minimise bone loss may be important even in very elderly people.