Chewing and spitting associated with a protein sparing modified fast and psychosocial stressors.
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Adult↗
Biomedical subjects
G R Smith
Publications and source records attributed to G R Smith.
Enhancement of the infectivity of Fusobacterium necrophorum by other bacteria.
Necrobacillosis is caused by Fusobacterium necrophorum (FN), but other organisms are often present in the lesions. Their possible role was studied in experiments made with a virulent FN strain which, by itself, produced fatal necrobacillosis in mice provided that large doses (greater than 10(6) organisms, subcutaneously) were given. Mice were inoculated subcutaneously with FN suspended in sub-lethal doses (0.1 ml) of undiluted or diluted broth cultures of other bacteria. Undiluted culture of a strain of Escherichia coli reduced the infective dose of FN to less than 10 organisms; in the necrobacillosis lesions that developed, fusobacteria greatly outnumbered E. coli. A heat-killed preparation or sterile filtrate of E. coli culture had little if any effect on FN. Citrobacter freundii and comparatively small numbers of Corynebacterium (Actinomyces) pyogenes produced effects similar to that of E. coli. An alpha-haemolytic streptococcus, Pseudomonas aeruginosa, Bacteroides fragilis and Fusobacterium nucleatum also enhanced the infectivity of FN, though less strikingly than E. coli. FN increased the persistence in vivo of the alpha-haemolytic streptococcus and B. fragilis, and enabled the latter to multiply profusely.
Animals↗
The production of Clostridium botulinum toxin in mammalian, avian and piscine carrion.
Mice, birds (chicks, quail) and fish (rudd, goldfish) killed shortly after receiving 1300-2000 spores of Clostridium botulinum per os were incubated, usually at 23 degrees C for 7 days. A 10% (w/v) homogenate of each rotting carcass was then prepared, sterilized by membrane filtration, and assayed for toxin. In mouse carcasses a type C strain of C. botulinum usually produced greater than 2 X 10(5) mouse intraperitoneal LD/g; in fish carcasses it usually produced less--often much less--than 2 X 10(4) LD/g. Avian carcasses appeared to be intermediate between those of mice and fish in their ability to support toxigenesis. A type E strain of C. botulinum, unlike type C, produced toxin equally well in fish and mouse carrion, usually at a concentration of between 2 X 10(4) and 2 X 10(5) LD/g.
Animals↗
Necrobacillosis and immunity in mice.
The study arose from the recent finding that sub-lethal numbers of certain bacterial species greatly enhanced the infectivity of Fusobacterium necrophorum. A severe F. necrophorum infection in mice, cured with metronidazole, produced significant though slight resistance, which was demonstrable by challenge with a minute dose of F. necrophorum (less than 20 organisms) suspended in a sub-lethal dose of Escherichia coli (300 x 10(6) organisms) to enhance fusobacterial infectivity. In an earlier comparable experiment, challenge with F. necrophorum alone, in necessarily large doses (greater than or equal to 3 x 10(6) organisms), failed to demonstrate that a single cured fusobacterial infection gave rise to resistance; such an infection neither protected against the fatal necrobacillosis produced by challenge nor prolonged survival. A sub-lethal E. coli infection was also shown by challenge with a minute dose of F. necrophorum (less than 10 organisms), suspended in a sub-lethal dose of E. coli (152 x 10(6) organisms), to produce significant though slight protection against necrobacillosis. The degrees of resistance demonstrated were too slight to give any encouragement to the prospect of an effective necrobacillosis vaccine.
Animals↗
Strand specificity of DNA unwinding by RecBCD enzyme.
RecBCD enzyme (exonuclease V) of Escherichia coli unwinds DNA, frequently forming asymmetric structures with two single-stranded tails of unequal length abutting a single-stranded loop at the junction with double-stranded DNA. Their lengths are consistent with the longer tail being one strand of the duplex and the loop plus the shorter tail being the other strand. The strand polarity of the unwinding was determined by labeling the 3' or 5' ends of duplex DNA with biotinylated nucleotides, reacting the DNA with RecBCD enzyme, and distinguishing the labeled ends, in the electron microscope, by their binding to streptavidin-gold complex. The shorter tail was formed from the DNA strand with its 3' terminus at the duplex end where RecBCD enzyme entered. We conclude that RecBCD enzyme unwinds DNA by forming a loop on the strand with a 3' end at the entry point. This result is concordant with a previously proposed model of recombination, which we discuss.
Base Sequence↗
Meiotic recombination-deficient mutants of Schizosaccharomyces pombe.
A mutant screen employing the ade6-M26 recombination hotspot was developed and used to isolate Schizosaccharomyces pombe mutants deficient in meiotic recombination. Nine rec mutations were recessive, defining six complementation groups, and reduced ade6 meiotic recombination 3-fold to greater than or equal to 300-fold when homozygous. Three recessive rec mutations analyzed further also reduced meiotic intragenic recombination at ura4 on chromosome III and intergenic recombination between pro2 and arg3 on chromosome I. The observed non-co-ordinate reductions of the recombinant frequencies in the three test intervals suggest a degree of locus (or intragenic vs. intergenic) specificity of the corresponding rec+ gene products. None of the mutations specifically inactivated the ade6-M26 hotspot. Additional rec genes may be identified with these methods.
Crosses, Genetic↗
Distribution of Chi-stimulated recombinational exchanges and heteroduplex endpoints in phage lambda.
The recombination hotspot Chi, 5' G-C-T-G-G-T-G-G 3', stimulates the RecBCD recombination pathway of Escherichia coli. We have determined, with precision greater than previously reported, the distribution of Chi-stimulated exchanges around a Chi site in phage lambda. Crosses of lambda phages with single base-pair mutations surrounding a Chi site were conducted in and analyzed on mismatch correction-impaired hosts to preserve heteroduplex mismatches for analysis. Among phages recombinant for flanking markers, Chi stimulated exchanges most intensely in the intervals immediately adjacent to the Chi site, both to its right and to its left. Stimulation fell off abruptly to the right but gradually to the left (with respect to the orientation of the Chi sequence written above). We have also determined that Chi stimulated the formation of heteroduplex DNA, which frequently had one endpoint to the right of Chi and the other endpoint to the left. These data support a model of Chi-stimulated recombination in which RecBCD enzyme cuts DNA immediately to the right of Chi and unwinds DNA to the left of Chi; segments of unwound single-stranded DNA are sometimes, but not always, degraded before synapsis with homologous DNA.
Bacteriophage lambda↗
Promoting medication compliance in clients with chronic mental illness.
In assisting with the delivery of mental health services for clients with chronic illness, nurses' specific professional skills play an important role. Nurses are working with clients who have chronic mental illness and their families in large numbers in the hospital and the community. Psychoeducational programs serve the goal of rehabilitation by promoting healthy behavior and preventing further illness. The current widespread involvement by nurses in helping clients with chronic mental illness comply with medication regimens indicates the extent of the need for this type of intervention. An active relationship between nurse and client improves compliance. The relationship involves teaching clients and family members about mental illness, medication regimens, and methods for coping with day-to-day living and crises that arise. Responsibility for medication education invites nurses to become more involved in other aspects of client and family preparation for living with chronic mental illness. Nurses provide programs about medications and their effects, social and living skills, and family education for clients with chronic mental illness.
Adult↗
Health perceptions of primary care patients and the influence on health care utilization.
This prospective study was conducted to determine the influence of primary care patients' health perceptions on their utilization of health care services. Patients' health perceptions were measured using the RAND Corporation's General Health Perceptions Questionnaire. Physicians provided scores of how they thought the patients perceived their health and of actual physical and emotional health. Utilization data (number of office visits, number of telephone calls to the physician, and ambulatory charges) were evaluated for a 12-month period after completion of the questionnaire. Of 208 patients, 62 (30%) patients with health perceptions scores less than 50 had greater degrees of anxiety (P less than .001), depression (P less than .001), health-related worry (P less than .001), and felt less able to resist illness (P less than .001) than patients with higher health perception scores. Analysis of covariance was used to control for differences in physical health among groups of patients with varying health perceptions. These analyses revealed that patients with low health perceptions made more office visits (P = .002), more telephone calls to the physician (P = .01), and had more office charges (P = .05) than patients with higher scores. Physicians accurately predicted the patients' health perceptions in 49% of the cases. In 37%, they thought patients would score their health perceptions higher than they did; in 14% they thought patients would score their health perceptions lower. Health perceptions are an important factor contributing to the use of health care by primary care patients, regardless of the patient's actual physical health. Persons with low health perceptions account for approximately 5% of office visits, a clinically important fraction, especially when compared to the 9% of office visits for hypertension, the most common disease treated in the medical office.
Adolescent↗
Homologous recombination in prokaryotes: enzymes and controlling sites.
A common step in prokaryotic recombination appears to be the synapsis of the 3'-end of single-stranded DNA with duplex DNA to form a D-loop. The enzymatic mechanisms by which 3'-ends are produced and by which D-loops are converted into recombinant molecules are illustrated by proposed mechanisms of recombination by the Escherichia coli RecBCD pathway and the phage lambda Red pathway. The enzymes promoting recombination and the special DNA sites at which they act are emphasized. Recombination by other E. coli pathways and in other prokaryotes is compared with these mechanisms.
Bacteria↗
Birth order of patients with DSM-III-R somatization disorder.
A sample of 143 patients, 76 meeting strict DSM-III-R criteria for somatization disorder and 67 somatizers, was studied using Slater's index to measure birth order position. The results showed that birth order position was not associated with the diagnosis of somatization disorder and that sibship position in both groups occurred by chance. Thus, although environmental factors may influence the development of somatization disorder, the expression of environmental influence through birth order is unlikely.
Adult↗
Developing an outcomes management strategy for the treatment of depression.
From a variety of perspectives and for numerous reasons, the U.S. medical care system is in crisis. Most of the efforts in recent years to improve quality and control costs have met with only modest, if any success. Recently, Ellwood outlined a new approach to making decisions in the medical care system which has the potential of addressing the problems with the system. This approach, called Outcomes Management, seeks to systematically assess the patient's outcome from a health status perspective as well as using traditional methods. These health status measures are both generic and disease-specific. This paper describes the approach to and general outline of a disease-specific measure for depression. The measure assesses patients at baseline and at periodic outcome points as well as collecting information about the treatment that the patient receives.
Depression↗
Speaking out. More power to you.
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Humans↗
Return to work after a first myocardial infarction. A test of multiple hypotheses.
The relationship between return to work within one year after a first myocardial infarction and selected sociodemographic, health, psychosocial, and vocational characteristics was assessed in 151 patients aged 24 to 70 years. Seventy-two percent of the sample returned to work. Education, physical activity associated with employment, severity of myocardial infarction, perception of health status, financial incentives, socioeconomic status, treatment hospital, rated social health status, locus of control, satisfaction with work, and early entry into the job force each proved to be significantly associated with return to work in independent univariate analyses. A stepwise multivariate regression analysis identified only the first four factors as important predictors of return to work. Further analyses show that given knowledge of the patients' educational level and the physical activity associated with employment, 71% of patients who returned to work were correctly classified. Return to work proved easier to predict than work disability. More knowledge is needed about the factors that are critical to a failure to resume employment after a myocardial infarction.
Adult↗
Traumatic Eagle's syndrome: report of a case and review of the literature.
A case of a styloid process fracture, or traumatic Eagle's syndrome is reported, and a review of the literature is provided. Although most patients with this rare type of fracture are treated with conservative therapy, some require surgical removal of the fractured process to alleviate their symptoms. This was necessary in the patient described.
Adult↗
Factors affecting the toxicity of rotting carcasses containing Clostridium botulinum type E.
Mice killed shortly after receiving c. 2000 spores of a type E strain of Clostridium botulinum per os were incubated at one of five chosen temperatures together with bottles of cooked meat medium seeded with a similar inoculum. After incubation the rotting carcasses were homogenized. Sterile membrane filtrates of the homogenates (10%, w/v) and pure cultures were then titrated for toxicity. Some of the main findings were confirmed with two further type E strains. Toxicity produced at 37 degrees C was poor in both carcasses and cultures (200-20,000 mouse intraperitoneal LD/g or ml). It was good in both systems at 30 and 23 degrees C, usually reaching 20,000-200,000 LD/g or ml, and in carcasses occasionally more; at 30 degrees C maximal toxicity was reached more quickly in carcasses than in cultures. Prolonged incubation (36-118 days) at 30 or 23 degrees C resulted in complete loss of toxicity in virtually all carcasses but not in cultures. At 16 degrees C the development of toxicity in carcasses was strikingly greater than in cultures. At 9 degrees C neither system produced more than slight toxicity after prolonged incubation. Trypsinization increased the toxicity of cultures but not usually of carcasses. Unfiltered carcass homogenate (10%, w/v) with maximal intraperitoneal toxicity was harmless for mice by mouth in doses of 0.25 ml. These findings differed in important respects from those made earlier with a type C strain.
Animals↗
Genetic and physical analysis of the M26 recombination hotspot of Schizosaccharomyces pombe.
The ade6-M26 mutation of Schizosaccharomyces pombe has previously been reported to stimulate ade6 intragenic meiotic recombination. We report here that the ade6-M26 mutation is a single G----T nucleotide change, that M26 stimulated recombination within ade6 but not at other distinct loci, and that M26 stimulated meiotic but not mitotic recombination. In addition, M26 stimulated recombination within ade6 when M26 is homozygous; this result demonstrates that a base-pair mismatch at the M26 site was not required for the stimulation. These results are consistent with the ade6-M26 mutation creating a meiotic recombination initiation site.
Crosses, Genetic↗
Panic and nausea instead of grief in an adolescent.
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Adolescent↗