Biomedical subjects
D Roberts
Publications and source records attributed to D Roberts.
Cyclic AMP-independent secretion of mucin by SW1116 human colon carcinoma cells. Differential control by Ca2+ ionophore A23187 and arachidonic acid.
The regulation of mucin secretion by SW1116 human colon carcinoma cells has been studied using monoclonal antibody 19-9, which has previously been used to detect mucin in the serum of cancer and cystic fibrosis patients. We found that SW1116 cells constitutively secrete considerable amounts of mucin as the predominant glycoprotein. The secretion of mucin by these cells is independent of cyclic AMP levels, but can be further stimulated by the Ca2+ ionophore A23187. However, arachidonic acid and its metabolites inhibit mucin secretion. Electron microscope studies reveal that the mucin is located near the plasma membrane as well as in vesicular and lysosome-like structures. However, the secretion pathway of mucin is different than that of the lysosomal contents, since arachidonic acid, while inhibiting mucin secretion, actually activates the secretion of the lysosomal enzyme beta-glucuronidase. We suggest that the mechanism of mucin secretion by SW1116 cells occurs by a pathway different from common exocytosis, and possibly by more than one pathway. The response of mucin secretion by SW1116 cells to common secretagogues resembles that of epithelial cells obtained from cystic fibrosis patients. Thus SW1116 cells are an especially interesting system for studying processes related to pathological states associated with excessive constitutive secretion of mucin.
Fetal echocardiography: accuracy and limitations in a population at high and low risk for heart defects.
OBJECTIVE: Our objective was to assess the accuracy of prenatal echocardiography in detecting congenital heart defects in patients at high and low risk for structural cardiac anomalies. STUDY DESIGN: Sixty-nine consecutive fetuses with congenital heart defects who had had prenatal ultrasonography at greater than or equal to 18 weeks' gestation were evaluated to determine the accuracy of prenatal ultrasonography in identifying structural cardiac defects. Thirty-nine patients were at high risk and 30 patients were at low risk for cardiac anomalies. All fetuses were scanned with standard four-chamber and outflow tract views. Data concerning extracardiac anomalies and karyotypic abnormalities were tabulated. The accuracy of the four-chamber view alone in identifying congenital heart defects was evaluated. RESULTS: Fifty-seven of 69 fetuses (83%) were prenatally identified ultrasonographically as having a heart defect. There was no difference in the sensitivity of detecting cardiac anomalies between high-risk and low-risk groups. When the four-chamber view was used, only 63% of fetuses were recognized as having an abnormal heart. Extracardiac anomalies were noted in 36% and karyotypic abnormalities in 17% of patients. CONCLUSION: The four-chamber and outflow tract views done routinely in an ultrasonography laboratory seeing a mixed population of patients was successful in detecting 83% of fetuses with structural cardiac malformations. Because 43% of the fetuses with heart defects were referred for low-risk indications, systematic ultrasonographic examination of the fetal heart should not be reserved only for those at high risk.
Influence of alprostadil on pulmonary dysfunction after a cardiac operation.
To test the effects of alprostadil on pulmonary dysfunction after cardiac operations, we studied 24 male patients undergoing aortocoronary bypass. Twelve were given an intravenous infusion of alprostadil (synthetic prostaglandin E1), 20 ng.kg-1.min-1, in a double-blind manner during operation; the other 12 were controls. Duration of artificial respirator use and frequent blood gas analyses were used to assess postoperative pulmonary function. Use of the artificial respirator postoperatively was significantly lower in the prostaglandin group (mean time. 5.25 +/- 1.81 hours) compared with the controls (mean time, 8.34 +/- 4.35 hours) (p = 0.047). The proportion of patients with hypercapnia and with hypoxia determined every 4 hours for the first 24 hours after extubation was significantly lower in the prostaglandin group compared with the controls (p less than 0.0001). These results indicate that synthetic prostaglandin E1 may play a role in protecting lung tissue during extracorporeal circulation.
An outbreak of Salmonella dublin infection in England and Wales associated with a soft unpasteurized cows' milk cheese.
An outbreak of Salmonella dublin infection occurred in England and Wales in October to December 1989. Forty-two people were affected, mainly adults, and most lived in south-east England. Microbiological and epidemiological investigations implicated an imported Irish soft unpasteurized cows' milk cheese as the vehicle of infection. A case-control study showed a statistically significant association between infection and consumption of the suspect cheese (p = 0.001). Salmonella dublin was subsequently isolated from cheeses obtained from the manufacturer's premises. Initial control measures included the withdrawal of the cheese from retail sale and a Food Hazard Warning to Environmental Health Departments, as well as a press release, from the Department of Health. Subsequently, a decision was taken by the manufacturer to pasteurize milk used in the production of cheese for the UK market and importation of the cheese resumed in June 1990.
Physical, physiological and performance differences between Canadian national team and universiade volleyball players.
Volleyball has been described as an 'interval' sport with both anaerobic and aerobic components. At the higher skill levels, technical performance may be limited by physical characteristics as well as physical fitness, and performance characteristics such as speed and vertical jump. This investigation compared teams at the two uppermost levels of men's volleyball in Canada for differences in physical, physiological and performance characteristics. The subjects were members of the national (n = 15) and universiade teams (n = 24). The parameters examined included percent body fat, maximal oxygen uptake (VO2 max), anaerobic power, bench press, 20-m sprint time and vertical jumping ability. The only significant difference in physical characteristics between the two teams was in age. Despite similarities in standing and reach height, the national team players had significantly higher block (3.27 vs 3.21 m) and spike (3.43 vs 3.39 m) jumps. An evaluation of anaerobic power measures produced similar power outputs during a modified Wingate test, yet the national team members had higher scores (P less than 0.05) for spike and block jump differences as well as 20-m sprint time. The large aerobic component of elite volleyball play was supported by the high VO2 max value recorded for the national team players (56.7 vs 50.3 ml kg-1 min-1). The results suggest that either years of specific physical conditioning and playing or the selection of individuals for the national team who possess more desirable characteristics as a consequence of genetic endowment, plays a significant role in the preparation of international calibre volleyball players.
Fully three-dimensional reconstruction from data collected on concentric cubes in Fourier space: implementation and a sample application to MRI.
An algorithm is proposed for rapid and accurate reconstruction from data collected in Fourier space at points arranged on a grid of concentric cubes. The Fourier transform of the object to be reconstructed is decomposed into the sum of three functions by subdividing its domain into three non-overlapping mutually orthogonal double pyramids. Each of the three functions is zero-valued outside one of the double pyramids and has values inside that double pyramid which are the same as those of Fourier transform of the object to be reconstructed at the same points. Inverse Fourier transforms of these individual functions can be calculated using the chirp z-transform. The outputs of these inverse transforms for the three functions are estimates of their values at points of the same rectangular grid. The function to be reconstructed is estimated for this grid by adding together the three inverse transforms. The whole process has computational complexity of the same order as required for the 3D fast Fourier transform and so (for medically relevant sizes of the data set) it is faster than backprojection into the same size rectangular grid. The design of the algorithm ensures that no interpolations are needed, in contrast to methods involving backprojection with their unavoidable interpolations. As an application, a 3D data collection method for MRI has been designed which directly samples the Fourier transform of the object to be reconstructed on concentric cubes as needed for the algorithm.
In utero infection due to Pasteurella multocida in the first trimester of pregnancy: case report and review.
To our knowledge, we report the first case of in utero infection in humans due to Pasteurella multocida in the first trimester of pregnancy. After antibiotic therapy was initiated, the mother recovered rapidly from bacteremia but the fetus was spontaneously aborted. Pathological examination of the fetus and placenta revealed acute deciduitis and chorionitis, indicating an infectious etiology for the abortion. The clinical and pathological features of this case are compared with those of the five previously reported cases of P. multocida bacteremia in humans that occurred during pregnancy.
Different vasodilating mechanisms--different peripheral effects?
Many factors, both local and systemic, are known to influence the caliber of peripheral vessels and regional blood flow. Methods of studying limb blood flow and its alteration by disease and drugs present considerable problems. We compared the effects of a series of antihypertensive drugs on limb blood flow and their functional effects in patients with hypertension and peripheral vascular disease. Results from studies with new antihypertensive drugs such as carvedilol are awaited.
Proportional assist ventilation. Results of an initial clinical trial.
The response to proportional assist ventilation (PAV) was tested in four normal subjects during heavy exercise and in five ventilator-dependent patients recovering from assorted medical disorders. The apparatus consisted of a rolling-seal piston coupled to a motor that generated pressure in proportion to inspired flow and inspired volume, with the gains adjusted such that the proportionality between airway pressure (Paw) and instantaneous patient-generated pressure (Pmus) was approximately 1:1 (i.e., machine-amplified patient effort by a factor of 2). Normal subjects responded to PAV by decreasing their own effort, as judged from esophageal pressure, such that the changes in ventilation and breathing pattern were rather small (VE: 64.8 +/- 3.6 during PAV versus 56.0 +/- 4.3, p less than 0.01; VT: 2.39 +/- 0.24 versus 2.02 +/- 0.17, p less than 0.05; f: 27.5 +/- 1.9 versus 28.0 +/- 2.2, NS). In patients, elastance ranged from 20 to 35 cm H2O cm/L, resistance ranged from 5 to 10 cm H2O/L/s, and maximal inspiratory pressure ranged from -16 to -65 cm H2O. After a period of observation during synchronized intermittent mechanical ventilation (SIMV) the patient was switched to PAV and maintained on it for 1 to 3 h. No patient had to be replaced on SIMV because of discomfort or deterioration in any of the monitored variables. During PAV peak airway pressure was less than half the value observed with the IMV breaths (16.6 +/- 2.4 versus 35.4 +/- 3.4 cm H2O, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
Cefaclor as a prophylactic agent for recurrent urinary infections: a comparative trial with macrocrystalline nitrofurantoin.
Eighty women with recurrent urinary infections (a median of seven episodes per year) were randomized to twelve months prophylaxis with cefaclor 250 mg or macrocrystalline nitrofurantoin 50 mg, at night. Seventy-three patients (37 given cefaclor and 36 given macrocrystalline nitrofurantoin) were assessable for efficacy. The incidence of radiological abnormalities in the two treatment groups was 23% and 30% respectively. Ninety-five percent of the patients taking cefaclor were symptomatically improved during the twelve months of prophylaxis and 86% remained abacteriuric; corresponding figures in the group taking macrocrystalline nitrofurantoin were 86% and 85% respectively. There were 88 breakthrough infections in patients taking cefaclor (6 resistant strains), and 9 in those patients taking macrocrystalline nitrofurantoin (6 by resistant strains). The mean interval between symptomatic episodes on prophylactic therapy increased by 5.6-fold in patients taking cefaclor, and 4.3-fold in those taking macrocrystalline nitrofurantoin. Resistant coliforms were found in only 3 out of 37 patients studied after twelve months prophylaxis; these organisms did not proceed to cause infections. All 80 patients were assessable for adverse events: 5 out of 39 taking cefaclor (12.8%) reported an event "probably" associated with the antibiotic, and 3 (7.7%) stopped taking the drug for various reasons; corresponding figures for macrocrystalline nitrofurantoin were 17.1% and 9.8% respectively. Patients with a radiological abnormality responded well to long-term low-dose prophylaxis with either agent. Cefaclor seems to offer an alternative to macrocrystalline nitrofurantoin for the prophylaxis of recurrent urinary infections in women.
Coverage by four information services of the core journals of rehabilitation and related topics.
In this study, three serials databases were used to identify core journals in rehabilitation and related areas. Simple strategies were used to search SERLINE (Serials Online, National Library of Medicine), Ulrich's International Periodicals Directory and SACHET (British Library serials database). Coverage of the journals identified by four secondary information services was then studied. These were Medline, Excerpta Medica, CINAHL (Cumulative Index to Nursing and Allied Health) and CATS (Current Awareness Topics Services, British Library). The results confirmed and extended the findings of earlier work: the number of core journals in rehabilitation is very large and their coverage by information services is very selective. Of the services studied here, CATS seemed to be most comprehensive for the journals identified.
Training at moderate altitude: iron status of elite male swimmers.
Laboratory evidence of suboptimal iron status is endemic in chronically training athletes, yet the importance of low serum ferritin values to athletic performance is unclear. The purpose of this study was to monitor iron status in nine male elite swimmers during and after a 3-week training camp at 2225 m altitude. Values for hemoglobin, hematocrit, serum iron, serum transferrin, and transferrin saturation were within the normal range and remained unchanged over the 54-day monitoring period. Serum ferritin level was significantly decreased by day 13 and continued to decline over the period at altitude. Significant recovery was observed by day 35, by which the workload and altitude were reduced. Reticulocyte counts were raised above normal values by the fifth day at altitude and remained elevated for the duration of the study, indicating increased erythropoiesis. In contrast, neither ferritin levels nor reticulocyte counts were changed in six of the nine subjects after 1 month's training at 1000 m. Food histories revealed dietary iron intakes two to three times as great as the recommended dietary allowance for iron. The draw on body iron reserves observed in this study over the heavy training period at moderate altitude indicates that adequate iron stores are necessary to provide a reservoir of iron during periods of increased iron utilization or loss. Further work is required to elucidate the sources and endpoints of the observed iron flux.
Efficacy of antiperspirants on feet.
Nineteen male soldiers participated in a study of the effectiveness of two antiperspirants (aluminum chlorohydrate and aluminum zirconium tetrachlorohydrex glycine) in reducing foot-sweat accumulation and injuries. Each subject was tested before and after antiperspirant application, with a 1-hour treadmill march at 5.6 km/hour in a warm environment. Both antiperspirants decreased (p less than 0.05) foot-sweat accumulation over 50%. There was also a tendency, although not statistically significant, for subjects to incur fewer blisters with antiperspirant use. However, the antiperspirants also increased (p less than 0.05) the incidence of irritant dermatitis. Nevertheless, these data suggest that the application of antiperspirants to the feet has merit in reducing serious foot injuries (blisters, trench foot) exacerbated by wet feet.
Physiotherapy exercises and back pain.
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Control of blood gas measurements in intensive-care units.
The frequency of blood gas measurement in two adult intensive-care units was assessed for 7 months before and 12 months after introduction of a protocol of indications for such investigation. Demographic, diagnostic, outcome, and intervention data were collected prospectively. There were no differences in demographic characteristics, severity or type of illness, survival, or frequency of arterial or pulmonary artery catheter use between the two observation periods, but the frequency of blood gas analysis fell by 44% (p less than 0.001) after the protocol was introduced.
Salmonella in chilled and frozen chicken.
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Excess number of bladder cancers in workers exposed to ortho-toluidine and aniline.
A retrospective cohort study of the incidence of bladder cancer was conducted in response to a union request for an evaluation of a possible excess number of cases of bladder cancer at a chemical plant in western New York State. Workers at the plant were exposed to two potential bladder carcinogens--ortho-toluidine (o-toluidine) and aniline. Incidence rates of bladder cancer among workers at the plant were compared with those of the population of New York State (excluding New York City). Among all 1749 workers at the plant, 13 cases of bladder cancer were observed versus 3.61 expected [standardized incidence ratio (SIR) = 3.60; 90% confidence interval (CI) = 2.13-5.73]. Among the 708 workers who worked in areas in which o-toluidine and aniline were used, 7 cases were observed versus 1.08 expected (SIR = 6.48; 90% CI = 3.04-12.2). Among the 288 maintenance, shipping, and janitorial workers thought to have been possibly exposed, 4 cases were observed versus 1.09 expected (SIR = 3.66; 90% CI = 1.25-8.37). Among the remaining 753 workers who were probably not exposed, 2 bladder cancers were observed versus 1.43 expected (SIR = 1.39; 90% CI = 0.25-4.39). Increased risk of bladder cancer was strongly associated with increased duration of employment in the department where o-toluidine and aniline were used (P less than .001). Among workers with 10 or more years of employment in the department, the SIR was 27.2 (90% CI = 11.8-53.7). o-Toluidine is an animal carcinogen more potent than aniline and is known to produce bladder tumors in rats; hence, it is more likely that o-toluidine is responsible for the observed excess number of cases of bladder cancer, although aniline may have played a role.