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Biomedical subjects

S P Murphy

Publications and source records attributed to S P Murphy.

At least 37 records · Page 2Linked to original sources
PubMed1995

Cloning and subcellular localization of human mitochondrial hsp70.

We report the cloning, nucleotide sequence, and localization of mitochondrial hsp70, a member of the human hsp70 multi-gene family. The human mthsp75 gene was cloned by screening an expression library with monoclonal antibody 3A3 that recognizes three members of the human hsp70 family (hsp70, hsc70, and a 75-kDa protein with characteristics identical to that previously established for mitochondrial hsp70). The identity of the 75-kDa protein was confirmed by subcellular fraction of HeLa cells and the demonstration that the 3A3-reactive 75-kDa protein co-fractionates with mitochondrial localized proteins. The nucleotide sequence of the respective cDNA clone revealed an open reading frame of 679 amino acids with extensive sequence identity with members of the human hsp70 family. The derived amino-terminal pre-sequence shares features common to other mitochondrial targeting sequences. The identity of the cDNA was unequivocally established by introduction of an epitope-tag at the carboxyl terminus of the cloned gene, transfection and analysis by immunofluorescence. The tagged 75-kDa protein localizes to mitochondria, thus providing conclusive evidence that it corresponds to the human mitochondrial hsp70, referred to here as mthsp75.

Amino Acid Sequence↗
PubMed1995

Activation of multiple transcription factors and fos and jun gene family expression in cells exposed to a single electric pulse.

We report that exposure of cells to a single electric pulse (250-1250 V/cm) results in the rapid and persistent activation of the DNA binding activities of a number of transcription factors, including AP-1, SP1, AP-2, and NF-kappa B, and the transient expression of select members of the fos and jun gene families. Induction of gene expression occurs primarily at the level of transcription, although c-jun expression also appears to be regulated posttranscriptionally. Interestingly, maximal induction of gene expression is detected at electrical field strengths that do not result in pore formation in the plasma membrane and that do not significantly affect cell viability. Exposure of cells to electric pulses does not result in the activation of HSF1 DNA binding activity, or the induction of hsp70 or p53 protein synthesis, indicating that the induction of fos and jun gene expression is not coincident with protein or DNA damage. The results of these studies suggest that electrical pulses may represent a novel mechanism for inducing the activities of multiple transcription factors and the expression of select members of the fos and jun gene families.

3T3 Cells↗
PubMed1995

Comparison of transtracheal and extravascular Doppler determinations of stroke volume and cardiac output at various states of volume loading in piglets.

OBJECTIVE: To assess the applicability of a new technology in neonates. Transtracheal Doppler and extravascular Doppler determinations of stroke volume and cardiac output were compared with thermodilution measurements at various states of volume loading in an animal model. DESIGN: Prospective, descriptive study. SETTING: Animal research laboratory at a university medical center. SUBJECTS: Fourteen newly weaned piglets, weighing 2.8 to 6.5 kg. INTERVENTIONS: Doppler probes were placed on the endotracheal tube tip (transtracheal Doppler) and directly on the aortic adventitia (extravascular Doppler). A 4-Fr thermodilution catheter was inserted in the pulmonary artery. Stroke volume and cardiac output determinations were recorded at baseline, after a 15-mL/kg volume load and after successive 15-mL/kg blood withdrawals to exsanguination or a systolic blood pressure of < 20 mm Hg. MEASUREMENTS AND MAIN RESULTS: Transtracheal and extravascular Doppler measurements of cardiac output were not significantly different from thermodilution at any physiologic state. These techniques were able to measure stroke volumes and cardiac outputs at the low levels seen in severe hemorrhagic shock. CONCLUSIONS: Transtracheal Doppler and extravascular Doppler measurements of cardiac output compare favorably with thermodilution. These methods effectively followed trends from alterations in intravascular volume, even at very high heart rates and small stroke volumes. Transtracheal Doppler and extravascular Doppler should yield useful information in critically ill neonatal patients, where data regarding stroke volume and cardiac output may be useful in clinical management.

Animals↗
PubMed1995

Schoolchildren have similar predicted prevalences of inadequate intakes as toddlers in village populations in Egypt, Kenya, and Mexico.

OBJECTIVES: To examine the probability of inadequacy of schoolchild nutrient intakes; to compare the predicted adequacy of schoolchild diets to previously published data for toddler diets and to examine the relative adequacy of the diets of sibling pairs. DESIGN: Food consumption data were measured 2 days per month across approximately one year. Mean nutrient intakes were calculated and compared to international standards using a probability approach. SETTING: Villages in Egypt, Kenya, and Mexico. SUBJECTS: 285 school-age children (7-9 years of age) and 255 toddlers (18-30 months of age) including 94 sibling pairs. RESULTS: Within a country, there was a striking similarity between the nutrients predicted to be inadequate in schoolchild and toddler diets across all nutrients except vitamin B12, which was more likely to be inadequate among schoolchildren. Nutrients of concern for both ages in one or more countries included iron, zinc, calcium, riboflavin, and vitamins B12, D, E, and A. For 94 toddler-schoolchild pairs, siblings at high risk of nutrient inadequacy could be identified from an indicator child with a sensitivity of 43-100% and a specificity of 59-100%. CONCLUSIONS: Nutrient adequacy tends to be a household characteristic for these two ages of children. Nutritional interventions that target the household have a high probability of benefitting multiple age groups of children.

Child↗
PubMed1994

Small subclass of rat olfactory neurons with specific bulbar projections is reactive with monoclonal antibodies to the HSP70 heat shock protein.

As part of a study of turnover of rat olfactory receptor neurons we have been examining immunohistochemical expression of members of the 70 kD heat shock protein (HSP70) family in the olfactory epithelium. Expression of HSP70 family members is up-regulated in many cells following exposure to physiologically stressing conditions. Because dying neurons are likely to undergo some sort of physiological stress before the onset of frank degeneration, we hoped that anti-HSP70 monoclonal antibodies would prove to be useful markers for early stages of olfactory neuron cell death. Two anti-human HSP70 monoclonal antibodies were used, Mabs 2A4 and 3a3. Two-dimensional gel electrophoresis/western blot analysis indicates that these Mabs are reactive with the HSC70 and HSP70 members of the rat HSP70 family. Immunohistological observations show that both Mabs are strongly reactive with a widely dispersed subpopulation of olfactory receptor neurons. Morphological, immunohistological, and autoradiographic birthdating analyses demonstrate that reactive cells are fully mature receptor neurons. Their reactivity, however, does not appear to be stress-related. More significantly, axons of reactive neurons show intense anti-2A4 reactivity. This has allowed us to trace these axons to their target glomeruli in the olfactory bulb, demonstrating that the reactive neurons project to just one to two glomeruli on either side of each bulb via consistent and predictable pathways. This is the first subpopulation of olfactory receptor neurons to be traced to such a small number of glomeruli. Given this extremely small number, it seems likely that the reactive receptor cell subpopulation serves some specific olfactory function. In addition, axonal 2A4 reactivity should also prove useful in defining the relative roles of receptor neurons and glomeruli in the establishment of epithelial-glomerular connections.

Animals↗
PubMed1994

Deficient induction of human hsp70 heat shock gene transcription in Y79 retinoblastoma cells despite activation of heat shock factor 1.

One of the basic features of the inducible heat shock response is the activation of heat shock factor which results in the rapid transcriptional induction of the heat shock genes. Although it is widely considered that the heat shock response is ubiquitous, several reports have indicated that the transcriptional response can vary in both intensity and kinetics and often in a tissue-specific manner. Of interest have been studies on the expression of heat shock genes in the brain, particularly observations that certain cultured neuronal cells exhibit a diminished heat shock response. We demonstrate that transcription of the gene encoding a 70-kDa heat shock protein (hsp70) is diminished upon heat shock in Y79 human retinoblastoma cells (which are of neuronal origin) despite both the activation of heat shock factor 1 and induced transcription of another heat shock gene, hsp90 alpha. This uncoupling of stress-induced transcription of the hsp70 and hsp90 alpha genes, which are typically coordinately regulated in response to stress, appears to be due to the selective inability of trans-acting factors, including heat shock factor 1, to bind in vivo to the hsp70 promoter as the result of a chromatin-mediated effect.

DNA-Binding Proteins↗
PubMed1994

Health behaviors and survival among middle-aged and older men and women in the NHANES I Epidemiologic Follow-up Study.

BACKGROUND: Since the 1960s there has been a decline in mortality rates for older U.S. adults, suggesting the importance of examining the role of prevention and health promotion in improving the health and survival of older adults. Epidemiologic studies of age and gender differences in the impact of health behaviors on survival for older U.S. adults are needed to provide information for intervention and health promotion efforts for older Americans. METHODS: We examined whether health behavior risk factors (smoking, drinking, physical activity, and body weight) for mortality vary by age and gender among 6,109 adults 45-74 years old in the National Health and Nutrition Examination Survey 1971-1975 (NHANES I) who were traced during the 1982-1984 NHANES I Follow-up Survey. RESULTS: For middle-aged men (45-54 years old) and for older men (65-74 years old), both smoking and nonrecreational physical activity were predictors of survival time. Additionally, for older men, drinking and low body mass index were associated with shorter survival time. Among women, there was less consistency of associations across age groups. As with men, nonrecreational physical activity and low body mass index were associated with shorter survival among older women. CONCLUSIONS: These findings suggest that health behaviors are associated with survival in older adults as well as in middle-aged adults, although the specific behavioral risk factors may vary by age and gender.

Adult↗
PubMed1994

Cefquinome (HR 111V). In vitro evaluation of a broad-spectrum cephalosporin indicated for infections in animals.

Cefquinome (formerly HR 111V), an aminothiazolyl cephalosporin, was compared with cefepime, cefpirome, cefotaxime, and ceftazidime against 681 clinical cultures and a challenge set of bacteria with well-characterized resistance mechanisms. Cefquinome minimum inhibitory concentrations (MIC90) for the enterobacteriaceae ranged from < or = 0.12-2 micrograms/ml with the highest MIC (4 micrograms/ml) obtained among Citrobacter freundii, Enterobacter cloacae, and Providencia stuartii strains. A total of 90% of the Pseudomonas aeruginosa were inhibited by cefquinome at < or = 8 micrograms/ml. Cefquinome activity of particular note for Gram-positive isolates included Corynebacterium jeikeium (MIC90, 8 micrograms/ml) and enterococci (MIC50, 4-8 micrograms/ml). Oxacillin-resistant Staphylococcus aureus was 32-fold less susceptible (MIC90, 16 micrograms/ml) to cefquinome than oxacillin-susceptible (MIC90, 0.5 micrograms/ml) strains. Cefquinome was very potent against fastidious isolates such as Moraxella catarrhalis (MIC90, 0.25-2 micrograms/ml); Haemophilus influenzae (MIC90, 0.06-1 micrograms/ml), Neisseria gonorrhoeae (MIC90, 0.06-0.5 micrograms/ml), and Streptococcus species (MIC90, < or = 0.03-006 micrograms/ml). When tested against organisms possessing Bush group 2 enzymes (including extended spectrum beta-lactamases), cefquinome remained active (MIC, < or = 8 micrograms/ml) against the majority of strains. This compound should be very active against pathogens generally found in animal infections and possesses a potency and spectrum comparable to the "fourth-generation" cephalosporins (cefepime and cefpirome) being investigated for human infectious diseases.

Animals↗
PubMed1994

Transtracheal Doppler in infants and small children following surgery for congenital heart disease: rational use of an improved technology.

OBJECTIVE: To compare measurements of cardiac output utilizing an improved transtracheal Doppler technology with measurements obtained using two-dimensional echocardiography. DESIGN: Prospective, descriptive study. SETTING: Cardiovascular intensive care unit at a university medical center. PATIENTS: Fourteen children ranging in age from 14 days to 3 yrs (mean 1.3 +/- .97 yrs) following surgery for complex congenital heart disease. INTERVENTIONS: Simultaneous cardiac output determinations using transtracheal Doppler and two-dimensional echocardiography were compared. Cardiac output was determined using measurement of blood velocity and diameter of the ascending aorta following surgery. Direct aortic diameter measurements made at operation were compared with measurements obtained by transtracheal Doppler, two-dimensional echocardiography and angiography. RESULTS: The mean difference in aortic root diameter between measurements made directly at operation and transtracheal Doppler was 5%, compared with 13% by two-dimensional echocardiography, and 21% by angiography, a significant difference by analysis of variance (F[3,31],p < .007). Post hoc comparisons demonstrated significant (p < .05) differences between echocardiography and angiographic aortic diameters. The mean difference between transtracheal Doppler and echocardiographic determination of cardiac output was 10.9% (t[10] = -1.37, p = .007). CONCLUSIONS: An improved transtracheal Doppler technology compares favorably with echocardiographic determination of cardiac output in infants and young children. This improved technology may provide a useful means to assess cardiac output and may allow titration of therapy in critically ill infants and children.

Aftercare↗
PubMed1994

Characterization of constitutive HSF2 DNA-binding activity in mouse embryonal carcinoma cells.

Two distinct murine heat shock transcription factors, HSF1 and HSF2, have been identified. HSF1 mediates the transcriptional activation of heat shock genes in response to environmental stress, while the function of HSF2 is not understood. Both factors can bind to heat shock elements (HSEs) but are maintained in a non-DNA-binding state under normal growth conditions. Mouse embryonal carcinoma (EC) cells are the only mammalian cells known to exhibit HSE-binding activity, as determined by gel shift assays, even when maintained at normal physiological temperatures. We demonstrate here that the constitutive HSE-binding activity present in F9 and PCC4.aza.R1 EC cells, as well as a similar activity found to be present in mouse embryonic stem cells, is composed predominantly of HSF2. HSF2 in F9 EC cells is trimerized and is present at higher levels than in a variety of nonembryonal cell lines, suggesting a correlation of these properties with constitutive HSE-binding activity. Surprisingly, transcription run-on assays suggest that HSF2 in unstressed EC cells does not stimulate transcription of two putative target genes, hsp70 and hsp86. Genomic footprinting analysis indicates that HSF2 is not bound in vivo to the HSE of the hsp70 promoter in unstressed F9 EC cells, although HSF2 is present in the nucleus and the promoter is accessible to other transcription factors and to HSF1 following heat shock. Thus trimerization and nuclear localization of HSF2 do not appear to be sufficient for in vivo binding of HSF2 to the HSE of the hsp70 promoter in unstressed F9 EC cells.

Animals↗
PubMed1993

Estimated vitamin intakes of toddlers: predicted prevalence of inadequacy in village populations in Egypt, Kenya, and Mexico.

Vitamin intakes of 255 toddlers (aged 18-30 mo) were estimated from food consumption recorded during 1 y at sites in Egypt, Kenya, and Mexico. Mean intakes were compared with requirements standards by using a probability approach to estimate the prevalence of inadequate intakes. There were predicted inadequacies for vitamin A (32%) and riboflavin (20%) in Egypt, vitamins A (68%) and C (63%) and riboflavin (52%) in Mexico, and vitamin B-12 (44%) in Kenya. Vitamin E was inadequate in all diets, but in relation to polyunsaturated fatty acids only the intake in Mexico was low. No diet provided the recommended amount of vitamin D, but its dietary requirement is uncertain. Correlations among nutrient intakes suggest factors that may contribute to reported associations of consumption of animal products with improved growth or development among these children: provision of vitamin B-12 and available minerals, displacement of fiber and phytate-rich energy sources, and increased energy density.

Avitaminosis↗
PubMed1993

Activation of heat shock gene transcription by heat shock factor 1 involves oligomerization, acquisition of DNA-binding activity, and nuclear localization and can occur in the absence of stress.

The existence of multiple heat shock factor (HSF) genes in higher eukaryotes has promoted questions regarding the functions of these HSF family members, especially with respect to the stress response. To address these questions, we have used polyclonal antisera raised against mouse HSF1 and HSF2 to examine the biochemical, physical, and functional properties of these two factors in unstressed and heat-shocked mouse and human cells. We have identified HSF1 as the mediator of stress-induced heat shock gene transcription. HSF1 displays stress-induced DNA-binding activity, oligomerization, and nuclear localization, while HSF2 does not. Also, HSF1 undergoes phosphorylation in cells exposed to heat or cadmium sulfate but not in cells treated with the amino acid analog L-azetidine-2-carboxylic acid, indicating that phosphorylation of HSF1 is not essential for its activation. Interestingly, HSF1 and HSF2 overexpressed in transfected 3T3 cells both display constitutive DNA-binding activity, oligomerization, and transcriptional activity. These results demonstrate that HSF1 can be activated in the absence of physiological stress and also provide support for a model of regulation of HSF1 and HSF2 activity by a titratable negative regulatory factor.

3T3 Cells↗
PubMed1993

Changes in energy intakes during pregnancy and lactation in a national sample of US women.

Increases in energy intakes during pregnancy and lactation were evaluated by examining dietary data for 458 pregnant women who participated in the Continuing Surveys of Food Intakes by Individuals conducted in 1985 and 1986. Energy intakes were well below recommendations during all reproductive states; however, increases during pregnancy approximated recommendations, while increases during lactation were low. Postpartum non-lactating intakes did not return to prepregnancy levels for Black women or women with lower incomes.

Adult↗
PubMed1992

Estimated protein intakes of toddlers: predicted prevalence of inadequate intakes in village populations in Egypt, Kenya, and Mexico.

This paper presents a probability assessment of the adequacy of protein intakes of toddlers (aged 18-30 mo) in study communities in Egypt, Kenya, and Mexico judged in relation to FAO/WHO/UNU estimates of requirements. Effects of supplementing amino acid intakes, or of assuming lower bioavailability for lysine are also considered. In Egypt and Mexico existing protein intakes of toddlers were adequate. In Kenya existing intakes were marginal. Total protein intake was low and often lysine or tryptophan concentration was low. If Kenyan intakes met estimated energy requirements, protein intakes would be adequate. We conclude that protein intake is unlikely to be a primary limiting factor for toddler growth and development, and the benefit to be expected from increasing the intake of limiting amino acids is marginal. Reported associations of animal-source protein and energy with growth, size, and psychologic function of these toddlers are unlikely to be causally attributable to inadequacy of protein intakes.

Amino Acids↗
PubMed1992

Estimated mineral intakes of toddlers: predicted prevalence of inadequacy in village populations in Egypt, Kenya, and Mexico.

Intakes of minerals and factors that might affect their bioavailability were estimated for 255 toddlers aged 18-30 mo living in villages in Egypt, Kenya, and Mexico. Mean intakes over 1 y were compared with international-requirement estimates by using a probability approach. The prevalence of iron intakes likely to be inadequate to prevent anemia was estimated as 35% in Egypt, 13% in Kenya, and 43% in Mexico. The prevalence of zinc intakes likely to be inadequate to meet basal requirements was estimated as 57% and 25% in Kenya and Mexico, respectively, but only 10% in Egypt, where the use of yeast-leavened breads was judged to have improved zinc availability. There was no suggestion that estimated copper or magnesium intakes were inadequate, but calcium intakes in Kenya and Egypt were well below recommended amounts. Studies of factors affecting mineral bioavailability in the diets of these countries' populations could suggest dietary changes that might improve effective mineral intake with minimal cost.

Calcium, Dietary↗