Biomedical subjects
Publications and source records attributed to T Baker.
The health problems of Maryland's agricultural migrant labor force are presented for the information of Maryland's health care providers. Maryland's problems are placed in the context of U.S. and worldwide migrant labor practices.
Bacteriophage lambda controls the expression of its early genes in a temporal manner by a series of transcription termination and antitermination events. This antitermination requires the lambda N protein as well as host proteins called Nus, and cis-acting sites called nut. Following transcription of the nut site, N and Nus proteins bind to the nut RNA and modify the transcription complex to a termination-resistant form. The nut site is a composite of at least two components; one is the boxB hairpin structure which interacts with N. The other is boxA, a nine-nucleotide sequence upstream of boxB. To understand more about the formation of the antitermination complex, we have characterized the effect of point mutations in and deletions of boxA on antitermination. Point mutations in boxA were found to either enhance or reduce N-mediated antitermination. Several boxA deletions, on the other hand, had little effect on antitermination other than to eliminate the requirement for the NusB host protein. To explain these observations, we propose that at least two factors compete to interact with boxA, NusB and an inhibitor of the antitermination reaction. In addition, we propose that NusB is required to prevent the inhibitor from binding at boxA. The results with various nusB and boxA mutations can be explained by this model of competition between NusB and an inhibitor for boxA RNA.
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Death from cancer results from the development of metastases or local progression of tumour. Metastasis and local progression may result from the inappropriate activity of metalloproteinases released by tumour cells or of their regulatory peptides. We have developed quantitative assays for interstitial collagenase, stromelysin 1 and tissue inhibitors of metalloproteinase (TIMP) 1 and 2, which have allowed the study of serum levels of these proteins. Sera from 40 patients with prostatic cancer, stored prior to and after 6 and 12 months' treatment with a gonadotrophin-releasing hormone agonist and an anti-androgen were analysed. Levels were compared with two control groups, comprising 21 patients with active rheumatoid arthritis and 56 age-matched hospital attenders without arthritis or cancer. Contrasting levels have been found in patients with prostatic cancer as compared with hospital controls without cancer and patients with rheumatoid arthritis. Patients with prostatic cancer had higher levels of TIMP-1 and collagenase (P = 0.0001) and lower levels of TIMP-2 (P = 0.003) than controls. Patients with metastatic cancer had significantly higher levels of collagenase than those without metastases (P = 0.02). Patients with rheumatoid arthritis had significantly higher levels of stromelysin than either controls (P = 0.002) or patients with cancer (P = 0.008). Serum tissue inhibitor of metalloproteinase 1 in combination with collagenase levels was as sensitive as prostate-specific antigen as a marker of metastatic disease. These findings provide a basis for the investigation of the role of metalloproteinases and their inhibitors in other malignancies.
Motor vehicle injuries are a major harmful side effect of industrialization. We examine this relationship in a rapidly industrializing country, Taiwan, using Potential Productive Years of Life Lost (PPYLL) analysis, and suggest ways that the injury toll of industrialization might be mitigated. We also compare Taiwan to the US, Hungary, Korea, and Chile. Taiwan has a higher PPYLL per 100,000 population due to motor vehicle injury (530/100,000) than cardiac disease, cancer, or strokes. Twenty-five years ago, more PPYLL was due to cancer, strokes, cardiac disease, and tuberculosis than to motor vehicle injuries (106/100,000). Taiwan's PPYLL rate is much greater than three other industrializing countries--Chile, Korea, and Hungary--and twice that of the US. Explanations for the dramatic rise in motor vehicle injury deaths in Taiwan may be high use of motorcycles, lack of motorcycle helmets, increase in alcohol use, high care density, and road and vehicle safety design problems.
It has long been recognized that a treatment for beta hemoglobin chain anomalies could result if a way to reverse the Hb F to Hb A switch in humans were found. Studies of hemoglobin switching have been hampered by the fact that small animals normally used in the laboratory do not have a true Hb F. However, several small animal models which take advantage of a switch in minor beta chain proportions in certain strains of inbred mice and rats have been proposed and used. The use of these models has suffered from what, until now, could be considered technically demanding, time-consuming methodologies. In this study we report an effective, rapid and technically streamlined model of hemoglobin switching utilizing Fisher 344 rats and high performance liquid chromatography with a weakly cationic column.
Many patients in the Surgical Holding Area become stressed and anxious. In a hospital setting music reduces patients' anxiety. This study determined that music can reduce the anxiety and stress of patients in the Surgical Holding Area. In this study, one group of subjects listed to music while a second group did not. Subjects who listened to music while in the Surgical Holding Area had significantly less stress and anxiety than did those who did not listen to music. Both groups spent similar lengths of time in the Surgical Holding Area. The results strongly suggest that if music were available to all patients in the Surgical Holding Area, most would select this option, and they would experience less anxiety.
The responses of several types of high-energy personnel neutron dosimeters were studied in the operational radiation fields at the Alternating Gradient Synchrotron. Included in the study are intercomparisons of polycarbonate, type A neutron track emulsion, allyl diglycol carbonate, electrochemical etch allyl diglycol carbonate, TLD-600, and TLD-700. Some of the passive measurements were compared with active tissue-equivalent instruments. The trend for many but not all of the measurements was for type A neutron track emulsion to report the highest neutron dose equivalent. The polycarbonate returned intermediate values while allyl diglycol carbonate usually reported the smallest values. Quality assurance data from calibration sources through 1990 are also provided.
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Two recent studies have implicated smoking as a principal risk factor for increasing the time patients spend in the postanesthesia care unit (PACU) following a wide range of surgical procedures. Hospitals are performing an increasing number of surgical procedures, with growing pressure to do more on an outpatient basis. With more internal and external pressures to streamline the rising costs of medical care, increased focus is being placed on the length of stay in the PACU. More than 300 patients were examined in each study. PACU time varied from 15 minutes to 5 hours, with a median of 75 minutes. Anesthesia duration correlated most closely with the length of stay in the PACU. All other variables were found to be unrelated to the length of time in the PACU or secondary to anesthesia time. The only independent factor was a history of smoking. While there were comparable ratios of smokers in all tested groups, there was a marked difference between smokers and nonsmokers in length of PACU stay. Of the nonsmokers, 38% were found to have PACU stays of less than 1 hour, compared with 23% of the smokers. Only 7% of the nonsmokers required longer PACU stays, compared with 19% of the smokers. Among the various smoking groups, however, there were no significant differences. While previous studies have suggested that smokers may have higher rates of various perioperative complications, these two studies are significant in that they have identified a population previously overlooked. These people who stay longer in the PACU would not otherwise be identified as having complications, and their eventual outcome was good. But it suggests that even these patients, who may view themselves as "healthy smokers," are significantly different from their nonsmoking counterparts. Further, varying the degree of smoking from heavy to light does not negate the increased PACU time. Therefore, any degree of smoking must now be viewed as having serious consequences in the immediate postoperative period and must be discouraged.
The mini-Tn10 transposon (delta 16 delta 17Tn10) confers tetracycline resistance. When inserted between a gene and its promoter, it blocks transcription and prevents expression of that gene. Tetracycline in the medium induces divergent transcription of the tetA and tetR genes within the transposon, and this transcription extends beyond the transposon in both directions into the bacterial genes. If the mini-Tn10 inserts between an essential bacterial gene and its promoter, the insertion mutation can cause conditional growth which is dependent on the presence of tetracycline. Two essential genes in adjacent operons of Escherichia coli have been detected by screening for tetracycline dependence among tetracycline-resistant insertion mutants. These essential genes are the era gene in the rnc operon and the dpj gene in the adjacent pdxJ operon. The pdxJ operon has not been described previously. It consists of two genes, pdxJ and dpj. Whereas the dpj gene is essential for E. coli growth in all media tested, pdxJ is not essential. The pdxJ gene encodes a protein required in the biosynthesis of pyridoxine (vitamin B6).
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Evaluated the impact that actions of significant others have on adjustment following rape. Significant other behavior is conceptualized as having two dimensions--supportive behavior and unsupportive behavior--and each dimension was measured using multiple items. Unsupportive behavior, but not supportive behavior, was found to bear a significant association to victim adjustment. Implications for those who work with victims are discussed.
Current studies of smoking prevention treat the adolescent as a target of influence, they emphasize the acquisition of skills for resisting peer pressure and give too little attention to motivation for resistance. Studies consistent with this social learning framework show moderate reductions in the incidence of smoking for the short term; recent, long-term follow-ups show no reduction in experimental over control conditions. We propose a re-examination of the influence framework and suggest that adolescents use smoking and dress, to project an image of self that will increase the likelihood of success in the formation of relationships in which participants share feelings and attitudes toward each other and the adult world. We also suggest that adults focus upon external, perceptible, and remote threats, e.g. smoking is seen as evil, a response to peer pressure, and a long term threat to health, and ignore discourse about proximal, subjective feelings respecting the changing sexual urges and feelings of social anxiety that accompany adolescence. The socialization of these affects is left to the peer group. It is suggested that future programs intensify their focus on motivation for resisting smoking based upon a revised view of the adolescents objectives in self definition, and combine this with the best of the current skills approaches.
Diurnal variation in leucocyte cystine and the effects of equimolar single doses of oral phosphocysteamine and rectal cysteamine were studied in eight patients with cystinosis, aged 1.8-16.5 years. No significant diurnal variation in leucocyte cystine was found. Absorption of cysteamine was reduced after rectal administration compared with the oral dose: mean (SD) peak concentration 17.2 (6.3) mumol/l v 36.4 (5.5) mumol/l at 40 min and mean (SD) area under the curve 22.3 (14.3) v 59.4 (33.1) mumol/h/l. Oral phosphocysteamine significantly reduced the mean (SD) leucocyte cystine from 8.09 (0.47) to 3.26 (1.48) nmol 1/2 cystine/mg protein at three hours. At 12 hours the mean leucocyte cystine was significantly lower than the pretreatment concentration. Rectal cysteamine did not significantly reduce the mean leucocyte cystine concentration. In conclusion, phosphocysteamine suspension may be administered every 12 hours. Rectal cysteamine administration is feasible but higher doses are required before efficacy can be judged.