Biomedical subjects
Publications and source records attributed to K A Baldwin.
A functional pyc gene was isolated from Lactococcus lactis subsp. lactis C2 and was found to complement a Pyc defect in L. lactis KB4. The deduced lactococcal Pyc protein was highly homologous to Pyc sequences of other bacteria. The pyc gene was also detected in Lactococcus lactis subsp. cremoris and L. lactis subsp. lactis bv. diacetylactis strains.
We identified a 14-kb pyruvate carboxylase gene-containing fragment from a lactococcal C2-lambda phage genomic library. Downstream of the pyruvate carboxylase gene-containing fragment, a gene cluster coding for open reading frames displaying extensive homology to citrate synthase, aconitase, and a truncated isocitrate dehydrogenase was identified. However, the truncation was shown to have occurred during the cloning by two noncontiguous Sau3AI fragments ligating together. The lactococcal citrate synthase gene consisted of 1323 bp and encoded a 441-amino acid citrate synthase protein. The lactococcal aconitase gene was 2544 bp and encoded an 848-amino acid protein. Corresponding to the complete citrate synthase gene, citrate synthase activity was detected in Lactococcus lactis ssp. lactis C2. Isocitrate dehydrogenase activity was found to be missing in Lactococcus lactis C2, suggesting that the gene may be incomplete or is not expressed, resulting in a requirement for glutamic acid in lactococci.
The purpose of this study was to determine the accessibility and perceived value of health services in five selected rural communities in South Fulton County, Illinois. The Health Services Accessibility and Value Scale (HSAVS) component of the larger Fulton County Health Care Survey was used in the investigation. The 12 items comprising the HSAVS surveyed participant perceptions relative to medical, dental, nursing, and public health department services available to them as rural residents. The HSAVS was completed by 1709 subjects. The reliability of the HSAVS was assessed by computing coefficient alpha. The scale had acceptable internal consistency reliability (alpha = .7884). To examine the construct validity of the scale, a principle component factor analysis was completed. This analysis resulted in a four factor solution which accounted for 66.6% of the cumulative total variance. Item means were calculated and were used to rank the HSAVS statements. Emergency and primary medical services were valued the most by the survey participants. Relatively high in importance to the rural residents surveyed were access to pharmacy, eye care, dental care, and immunization services. Availability of home health care, transportation to and from health care facilities, and access to mental health services were considered to be of lesser value to persons living in the rural area studied. Of least importance were alcohol and other drug counseling services, prenatal care/well baby services, and family planning services. HSAVS total scores and individual statements were also analyzed by sex, age, place of residence, and income and the results were reported.
The purpose of this study was to identify the significant dimensions of the concept of community acceptance of nurse practitioners/physician's assistants and to construct a reliable and valid instrument which would reflect these dimensions. The methodological approach included: conceptualization of categories, development of items for each category, development of the tool, administration of the tool, and psychometric analysis of results. Community input through focus-group interviews and post-administration questions provided qualitative data. The survey tool, consisting of items in four conceptualized categories (knowledge, access, competence, and trust), was administered in five rural communities. The responses of 967 residents were analyzed through factor analysis. The criterion, eigenvalue > or = 1.0, resulted in seven factors. Oblique rotation was applied to the seven factors and marker variables (loadings > .70) facilitated the identification of the underlying dimensions of each factor. Overall, 98% of the items assigned to the original categories were maintained after factor analysis. The identification of these dimensions helped to simplify the description and understanding of community acceptance of nurse practitioners and physicians' assistants. Community acceptance of these advanced health care providers is a necessary precursor to use of services.
Meeting the needs of HIV-infected patients in a focused, cost-efficient, coordinated manner is one of the most challenging problems in health care today. Before developing an intervention program, accurate surveys of need must be done. This article presents one such needs assessment conducted in a rural section of the Midwest. The assessment consisted of (1) surveys of HIV+ individuals/people with AIDS, area physicians, and local key informants and service providers, and (2) statistical data from health departments. Results of analyses suggest that access to primary care, self-care education, mental health and family support services, case management, financial assistance, community education, and home health services are this community's highest priority needs.
Nurse practitioners and physician assistants have provided a partial solution to the shortage of primary care services in medically underserved rural areas. This paper describes the results of a study exploring community acceptance of nurse practitioners and physician assistants in rural medically underserved areas. Community acceptance in the context of this study implies not only satisfaction with care received, but also willingness of the community to support NP/PA practice through its infrastructure and encourage members to initially seek and continue to receive care from an NP or PA. Five focus groups were conducted in each of five rural medically underserved communities. The two most pervasive findings were the lack of previous exposure to NPs and PAs and the general belief that NPs and PAs would be accepted in these communities if certain conditions could be met. The theme of conditional acceptance included both personal and system factors. Personal factors included friendliness, competence, willingness to enter into the life of the community, and the ability to keep information confidential. System factors considered critical for acceptance included service type, integration with the existing health care system, cost, geographic proximity, and availability. The results of this study offer insight into community attitudes and suggest marketing strategies for those who plan to introduce NP or PA services into rural communities.
The study compared the health beliefs of participants and non-participants in a blood pressure and cholesterol screening held at the worksite. A cross sectional, ex-post facto design was used. Questionnaires measuring health beliefs related to cardiac screening and prevention of cardiac problems were distributed to a convenience sample of 200 blue-collar workers in a large manufacturing plant in the Midwest. One hundred fifty-one (75.5%) completed questionnaires were returned, of which 45 had participated in cardiac worksite screening in the past month. A multivariate analysis of variance was used to analyze data. Participants perceived significantly fewer barriers to cardiac screening and scored significantly higher on self efficacy than non-participants. These findings concur with other studies identifying barriers and self efficacy as important predictors of health behavior. Occupational health nurses' efforts are warranted to reduce barriers and improve self efficacy by advertising screenings, scheduling them at convenient times and locations, assuring privacy, and keeping time inconvenience to a minimum.
Timing of initial public health nurse contact and number of nurse contacts were examined for their relationship to adequacy of prenatal physician care, infant birthweight, and gestational age. Three historical cohort groups were drawn from three downstate Illinois counties: 1) public health nursing clients (N = 506); 2) Women, Infant, and Children Nutrition Program clients (N = 314); and 3) clients receiving neither of these services (N = 403). Data were obtained from local health department records and a state birth certificate data tape. Descriptive statistics and logistic and multiple regression were used to analyze data. Timing of initial public health contact was significantly correlated to adequacy of prenatal physician contact and infant gestational age. No relationship was found between either timing of initial public health nursing contact or number of these contacts and infant birthweight. The number of public health nursing and physician contacts exerted an additive effect on birthweight and gestational age. Findings lend support for case-finding activities that result in public health nursing contacts early in pregnancy. The importance of multidisciplinary approaches to prenatal care is suggested.
Evidence is presented that lactose-fermenting ability (Lac+) in Lactococcus lactis subsp. cremoris AM1, SK11, and ML1 is associated with plasmid DNA, even though these strains are difficult to cure of Lac plasmids. When the Lac plasmids from these strains were introduced into L. lactis subsp. lactis LM0230, they appeared to replicate in a thermosensitive manner; inheritance of the plasmid was less efficient at 32 to 40 degrees C than at 22 degrees C. The stability of the L. lactis subsp. cremoris Lac plasmids in lactococci appeared to be a combination of both host and plasmid functions. Stabilized variants were isolated by growing the cultures at 32 to 40 degrees C; these variants contained the Lac plasmids integrated into the L. lactis subsp. lactis LM0230 chromosome. In addition, the presence of the L. lactis subsp. cremoris Lac plasmids in L. lactis subsp. lactis resulted in a temperature-sensitive growth response; growth of L. lactis subsp. lactis transformants was significantly inhibited at 38 to 40 degrees C, thereby resembling some L. lactis subsp. cremoris strains with respect to temperature sensitivity of growth.
The lactic acid bacteria are involved in the manufacture of fermented foods from raw agricultural materials such as milk, meat, vegetables, and cereals. These fermented foods are a significant part of the food processing industry and are often prepared using selected strains that have the ability to produce desired products or changes efficiently. The application of genetic engineering technology to improve existing strains or develop novel strains for these fermentations is an active research area world-wide. As knowledge about the genetics and physiology of lactic acid bacteria accumulates, it becomes possible to genetically construct strains with characteristics shaped for specific purposes. Examples of present and future applications of biotechnology to lactic acid bacteria to improve product quality are described. Studies of the basic biology of these bacteria are being actively conducted and must be continued, in order for the food fermentation industry to reap the benefits of biotechnology.
The effectiveness of public health nursing interventions with prenatal clients was summarized from 17 studies, conducted between 1963 and 1988, that were identified through a comprehensive reference search. The review indicated that public health nursing interventions can increase birthweight, and the use of prenatal medical services, nutritional services, and childbirth classes. Because of methodological problems, however, it is difficult to conclude with certainty that such interventions make a significant difference in client outcomes. These problems included lack of construct validity, lack of specification of interventions, small convenience samples, lack of power to detect small treatment effects, nonexperimental research designs, lack of reliability information, and self-selection and history biases. To overcome these problems, the authors suggest the use of conceptual frameworks, power calculations prior to initiation of research, experimental or quasiexperimental designs, replication of research with different populations, and the calculation and reporting of reliability information.
The mechanism of reduced sensitivity to the small isometric-headed bacteriophage sk1 encoded on a 19-kilobase (kb) HpaII fragment subcloned from pKR223 of Lactococcus lactis subsp. lactis KR2 was examined. The reduced sensitivity to phage sk1 was due to a modest restriction/modification (R/M) system that was not active against prolate-headed phage c2. The genetic loci for the R/M system against sk1 and the abortive phage infection (Abi) mechanism effective against phage c2 were then localized by restriction mapping, subcloning, and deletion analysis. The restriction gene was localized to a region of a 2.7-kb EcoRV fragment and included an EcoRI site within that fragment. The modification gene was found to be physically separable from the restriction gene and was present on a 1.75-kb BstEII-XbaI fragment. The genetic locus for the Abi phenotype against phage c2 was localized to a region containing a 1.3-kb EcoRI fragment. Attempts to clone the c2 Abi mechanism independent of the sk1 R/M system were unsuccessful, suggesting that expression of the abi genes required sequences upstream of the modification gene. Some pGBK17 (vector pGB301 plus a 19-kb HpaII insert fragment) transformants exhibited the R/M system against phage sk1 but lost the Abi mechanism against phage c2. These transformants contained a 1.2- to 1.3-kb insertion in the Abi region. The data identified genetic loci on a cloned 19-kb HpaII fragment responsible for restriction activity and for modification activity against a small isometric-headed phage and for Abi activity against prolate-headed phage c2. A putative insertion element was also found to inactivate the abi gene(s).
Succinylcholine (SCh) has been detected six months postmortem in liver, kidney, and injection site muscle of rats given 10 to 200 mg/kg by intramuscular injection. SCh stability was studied in canine tissue to evaluate three storage temperatures and two chemical preservatives at three time periods after injection. Nine mongrel dogs weighing 17.2 to 28 kg were divided equally into three groups and administered either 0.5, 1.0, or 5.0 mg SCh/kg intravenously into the cephalic vein. Liver, kidney, and gastrocnemius muscle were removed 90 min post-injection and divided into twelve portions. Each portion was treated with embalming fluid, physostigmine, the combination (50/50), or nothing. Chemically treated tissues and nontreated tissues were then stored at either 27, 5, or -20 degrees C for a period of up to forty days. Tissue portions were analyzed using ion-pair extraction, chemical demethylation, and gas chromatography with nitrogen phosphorous detection. Stability of SCh was greatest for samples stored at -20 degrees C and preserved with the combination of embalming fluid plus physostigmine. Kidney concentrations of SCh were significantly higher than those in liver or muscle at all doses. SCh was detected 24 h post-injection in all cases. By 40 days, only trace amounts of SCh, if any, could be detected in samples stored at room temperature with no chemical preservatives.
The study was undertaken to determine the pharmacokinetic values for half-life, volume of distribution, and clearance for succinylcholine (SCh) based on measurements of the drug in plasma. Three intravenous (i.v.) doses (0.5, 1.0, and 5.0 mg/kg) were compared to study the time course of paralysis and recovery and to describe the relationship of plasma concentration (Cp) and the pharmacologic effects of SCh in canines. The physiologic response to the neuromuscular blocking drug was monitored using train-of-four stimulation of the left sciatic nerve and recording the response of the corresponding gastrocnemius muscle. Time courses for paralysis and recovery were monitored, and the results were used to predict the kinetic values for the pharmacologic effects. Blood samples were taken following drug administration for direct pharmacokinetic estimations. SCh determinations were performed using ion-pair extraction, chemical demethylation, and gas chromatography with nitrogen phosphorous detection. Both kinetic analyses showed the beta half-life for SCh to be approximately 5 min for all doses. SCh has a distribution half-life of less than 1 min. There appears to be a threshold Cp below which neuromuscular function returns. Recovery following SCh induced paralysis had a rapid onset, but the duration of paralysis and the rate of recovery were especially prolonged for the 5.0-mg/kg treatment group.
Transduction for lactose-fermenting ability between the lactose-positive lysogen Streptococcus lactis LM0221 and plasmid-cured, prophage-cured, lactose-negative S. lactis LM2301 resulted in the appearance of lactose-positive transductants surrounded by a zone of clearing in the lactose-negative cell lawn. By using plaque assay procedures, the zones were shown to contain bacteriophage particles, and both spontaneous release and UV induction of prophage from these transductants were demonstrated. The DNA hybridization confirmed that LM2301 did not contain the prophage in its chromosome and that the zone-producing transductant KZ1 was relysogenized by the temperate bacteriophage. Further, a 4.35 Kb EcoRI digestion fragment appeared to contain the DNA sequences for integration into the chromosome and may provide a means for stabilizing cloned DNA by effecting chromosomal insertion in LM2301 derivatives. The selection of zone-producing lactose-positive transductants of LM2301 provided a means for detecting strains relysogenized by the temperate phage induced from LM0221.
Streptococcus lactis subsp. diacetylactis DRC3 was examined for plasmid DNA and found to contain a previously unreported plasmid of 40 X 10(6) daltons. This plasmid, designated pNP40, was conjugally transferred to a plasmid-cured derivative of S. lactis C2. Transconjugants containing pNP40 acquired resistance to nisin produced by strains of S. lactis and to commercially available nisin when assay plates were incubated at 21, 32, and 37 degrees C. In addition, c2 phage growth was completely restricted in transconjugants containing pNP40 at 21 and 32 degrees C, but not at 37 degrees C. This result suggests that pNP40 may be coding for a temperature-sensitive enzyme that restricts phage growth at 21 and 32 degrees C, but not at 37 degrees C. Eight consecutive transfers of a transconjugant containing pNP40 in Elliker broth at 37 degrees C resulted in 100% loss of resistance to c2 phage when colonies were tested at 32 degrees C. These phage-sensitive isolates had lost pNP40 and had also become sensitive to nisin. This result suggests that pNP40 may also be thermosensitive in its replication. The finding of a phage resistance determinant located on a conjugative plasmid should prove useful in constructing phage-resistant variants for dairy fermentation processes.
Streptococcus lactis subsp. diacetylactis strain WM4 transferred lactose-fermenting and bacteriocin-producing (Bac+) abilities to S. lactis LM2301, a lactose-negative, streptomycin-resistant (Lac- Strr), plasmid-cured derivative of S. lactis C2. Three types of transconjugants were obtained: Lac+ Bac+, Lac+ Bac-, and Lac-Bac+.S. diacetylactis WM4 possessed plasmids of 88, 33, 30, 5.5, 4.8, and 3.8 megadaltons (Mdal). In Lac+ Bac+ transconjugants, lactose-fermenting ability was linked to the 33-Mdal plasmid and bacteriocin-producing ability to the 88-Mdal plasmid. Curing the 33-Mdal plasmid from Lac+ Bac+ transconjugants resulted in loss of lactose-fermenting ability but not bacteriocin-producing ability (Lac- Bac+). These strains retained the 88-Mdal plasmid. Curing of both plasmids resulted in a Lac- Bac- phenotype. The Lac+ Bac- transconjugant phenotype was associated with a recombinant plasmid of 55 or 65 Mdal. When these transconjugants were used as donors in subsequent matings, the frequency of Lac transfer was about 2.0 X 10(-2) per recipient plated, whereas when Lac+ Bac+ transconjugants served as donors, the frequency of Lac transfer was about 2.0 X 10(-5) per recipient plated. Also, Lac- Bac+ transconjugants were found to contain the 88-Mdal plasmid. The data indicate that the ability of WM4 to produce bacteriocin is linked to an 88-Mdal conjugative plasmid and that lactose-fermenting ability resides on a 33-Mdal plasmid.
Eleven antibiotic compounds used in animal production, were compared with N,N-dimethyldodecanamine for their effects on in vitro cellulose digestibility and VFA production. Dose-response data were analyzed statistically to determine the concentration for each compound which would inhibit cellulose digestion of VFA production by 50%, thereby providing a convenient reference point for evaluation of the amine with respect to the antibiotics. Chlortetracycline, oxytetracycline and penicillin inhibited cellulose digestion by 17 to 35% and VFA production by 18 to 26% at concentrations of 2.5 micrograms/ml, while N,N-dimethyldodecanamine and dihydrostreptomycin at concentrations of 10 micrograms/ml inhibited cellulose digestion and VFA production by 5 to 19%. For similar inhibitive effects, bacitracin, chloramphenicol, kanamycin, sulfanilamide and sulfathiazole were required in concentrations of 25 micrograms/ml. Tylosin at a concentration of 1 microgram/ml inhibited cellulose digestion and VFA production by about 80 and 50%, respectively, and monensin was effective at 5 micrograms/ml. In general, compounds of lesser importance for growth promotion in ruminants (sulfathiazole, sulfanilamide and kanamycin) had a less inhibitory effect on cellular digestion and VFA production in vitro. N,N-dimethyldodecanamine was more effective than these compounds but repressed cellulolytic activity less than those antibiotics (chlortetracycline, oxytetraxycline and monensin) that are most effective in improving feed efficiency.