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Biomedical subjects

D L Murray

Publications and source records attributed to D L Murray.

At least 19 recordsLinked to original sources
PubMed2000

Development of a model to study Aspergillus fumigatus proliferation on the air cell membrane of in ovo injected broiler eggs.

A model was developed to examine the proliferation of Aspergillus fumigatus on the air cell membrane of broiler hatching eggs and to assay the effectiveness of fungal control strategies that may be used in conjunction with late embryonic egg injection. Egg yolk was identified as the nutritive media required to sustain fungal growth. Incubation was required to predispose the egg to fungal infection by allowing the yolk to come into contact with the air cell membrane. Infertile eggs and eggs containing embryos that died before 4 d of incubation (early-dead) that had been subsequently incubated for 9 d or more were equally susceptible to fungal infection. In order to evaluate potential methods of control, these eggs were punched through the blunt end of the shell with a 16-gauge needle, placed into forced-air incubators (hatchers), and exposed to air-dispersed pure cultures of A. fumigatus. The frequency of eggs exhibiting mold growth on the air cell membrane 72 h after exposure was subjected to a Chi-square analysis model. The effect of egg position within an incubator flat in relationship to the A. fumigatus source culture, the variation between flats (levels) within a given hatcher, the variation between hatchers, and the variation between replicate trials were measured and found to be potential sources of experimental error that must be minimized in order to accept the results of an evaluation. A statistically valid model was developed that can be used to evaluate various types of fungicidal treatments of hatching eggs and their relative efficacy in association with egg injection.

Animals↗
PubMed1999

Dental hygienists' knowledge of menopause and its potential oral manifestations.

PURPOSE: The purpose of this study was to assess dental hygienists' general knowledge of menopause and its possible oral manifestations. Demographic descriptors, including education level, course work, and menopausal status, were examined to determine their influence on knowledge levels. METHOD: A 27-item, self-administered survey was mailed to a random sample of Connecticut dental hygienists. Frequency distributions and inferential statistics (ANOVA, t-test) were used for data analysis. RESULTS: Fifty-four percent of respondents scored 75 percent or higher in general knowledge about menopause. Seven percent scored the same about its oral effects. Educational level and dental hygiene college curricula influenced the oral effect scores. Dental hygienists with bachelor degrees exhibited more knowledge than those with certificate/associate degrees. Those who had taken a college course on the oral effects of menopause had more knowledge than those who had not. CONCLUSION: The findings suggest that dental hygienists need more education about menopause and its related oral conditions. Those with additional knowledge might be more able to provide comprehensive care to menopausal and post-menopausal dental patients. Future research using larger sample sizes may enhance the education of dental hygienists in this area.

Analysis of Variance↗
PubMed1998

Structures of five mutants of toxic shock syndrome toxin-1 with reduced biological activity.

The three-dimensional structures of five mutants of toxic shock syndrome toxin-1 (TSST-1) have been determined. These mutations are in the long central alpha helix and are useful in mapping portions of TSST-1 involved in superantigenicity and lethality. The T128A, H135A, Q139K, and I140T mutations appear to reduce superantigenicity by altering the properties of the T-cell receptor interaction surface. The Q136A mutation is at a largely buried site and causes a dramatic change in the conformation of the beta7-beta9 loop which covers the back of the central alpha helix. As this mutation has the unique ability to reduce the toxin's lethality in rabbits while retaining its superantigenicity, it raises the possibility that this rear loop mediates the ability of TSST-1 to induce lethality and suggests a route for producing nonlethal toxins for therapeutic development.

Alanine↗
PubMed1998

The adverse effect of hydrosalpinges on in vitro fertilization pregnancy rates and the benefit of surgical correction.

OBJECTIVE: To test the hypothesis that IVF-ET pregnancy rates (PRs) for patients with tubal factor infertility are decreased in patients with hydrosalpinges and that surgical correction reverses this effect. DESIGN: Retrospective chart review. SETTING: Private practice IVF-ET program. PATIENT(S): Patients (n = 160) undergoing 238 cycles of IVF-ET were stratified into groups based on the presence of hydrosalpinges and whether surgical correction had been performed. Patients >39 years old and patients with male factor infertility were excluded from the study. INTERVENTION(S): Patients with hydrosalpinges were offered surgical correction. MAIN OUTCOME MEASURE(S): Clinical pregnancy defined by an intrauterine gestational sac. RESULT(S): Patients with hydrosalpinges had significantly decreased implantation rates and PRs per transfer (2.8% and 8.5%, respectively) than patients with tubal factor infertility but without hydrosalpinges (15.7% and 38.6%). Surgical correction improved implantation rates and PRs in patients with prior failed cycles (16.1% and 37.5%) and in patients undergoing surgery before IVF-ET (21.8% and 51.7%). The type of surgery performed did not affect success rates in the small number of patients evaluated. CONCLUSION(S): The presence of a hydrosalpinx during an IVF-ET cycle results in significant decreases in implantation rates and PRs. Surgical treatment of hydrosalpinges before IVF-ET cycles improves implantation rates and PRs.

Adult↗
PubMed1997

Development of a highly quantitative, reproducible assay for determination of chicken T cell growth factor biological activity.

This report examines optimal culture conditions necessary for accurate and sensitive quantification of chicken T Cell Growth Factor (TCGF) activity. With this bioassay, TCGF is quantified by measuring its ability to cause proliferation of splenocytes prestimulated with mitogen. Proliferation is quantified by determining the optical density (OD) or "signal" of test samples in microtiter wells by measuring the incorporation of tetrazolium salt by live cells. To optimize assay conditions, systematic evaluation of the effects of cell culture variables was carried out with the constant aim of increasing signal to noise ratio in the assay. Higher signal to noise ratios were found when using Dulbecco's Modified Eagle's Medium (DMEM) rather than Roswell Park Memorial Institute Medium (RPMI) for basal tissue culture media containing the same supplements. The addition of lipid supplement to the assay system not only increased the proliferation signal, but also decreased the background OD. Incubation temperatures of 41 C rather than 37 C for both the mitogen prestimulation and proliferation phases of the assay also resulted in a higher signal to noise ratio. While incorporating the optimal experimental conditions, a finalized assay procedure employing test sample normalization with an internal assay standard was tested for accuracy. The assay can accurately detect 2 to 15 U/mL of TCGF activity. The within-assay variation ranged from 2 to 13% and the between-assay variation ranged from 11 to 22% depending upon the TCGF preparation being tested. The excellent reproducibility of this assay has facilitated investigations of TCGF production, processing, and purification.

Animals↗
PubMed1996

Localization of biologically important regions on toxic shock syndrome toxin 1.

Toxic shock syndrome toxin 1 (TSST-1) contains a long central alpha helix that forms the base of two grooves on opposite sides of the molecule. Previous studies indicated that residues 132, 135, and 140 along the back of the central alpha helix are important in the biological activities. We made mutations of additional central alpha-helix residues exposed along this groove on the back of TSST-1. The proteins were purified, shown not to have gross alteration in structure, and tested for both superantigenicity and ability to elicit lethal TSS, using the superantigenicity, likely to because of alteration in T-cell receptor binding. Mutants H135A, Q136A, and E132K/ Q136K lost the ability to induce lethal TSS. The mutant Q136A was most increasing because it was superantigenic, yet nonlethal.

Animals↗
PubMed1995

Molecular structure of staphylococcus and streptococcus superantigens.

Staphylococcus aureus and streptococci, notably those belonging to group A, make up a large family of true exotoxins referred to as pyrogenic toxin superantigens. These toxins cause toxic shock-like syndromes and have been implicated in several allergic and autoimmune diseases. Included within this group of proteins are the staphylococcal enterotoxins, designated serotypes A, B, Cn, D, E, and G; two forms of toxic shock syndrome toxin-1 also made by Staphylococcus aureus; the group A streptococcal pyrogenic exotoxins, serotypes A, B, and C; and recently described toxins associated with groups B, C, F, and G streptococci. The nucleotide sequences of the genes for all of the toxins except those from the groups B, C, F, and G streptococcal strains have been sequenced. The sequencing studies indicate that staphylococcal enterotoxins B and C and streptococcal pyrogenic exotoxin A share highly significant sequence similarity; staphylococcal enterotoxins A, D, and E share highly significant sequence similarity; and toxic shock syndrome toxin-1 and streptococcal pyrogenic exotoxin B and C share little, if any, sequence similarity with any of the toxins. Despite the dissimilarities seen in primary amino acid sequence among some members of the toxin family, it was hypothesized that there was likely to be significant three-dimensional structure similarity among all the toxins. The three-dimensional structures of three of the pyrogenic toxin superantigens have been determined recently. The structural features of two of these, toxic shock syndrome toxin-1 and enterotoxin C3, are presented. Toxic shock syndrome-1 exists as a protein with two major domains, referred to as A and B. The molecule begins with a short N-terminal alpha-helix that then leads into a clawshaped structure in domain B that is made up of beta strands.

Bacterial Toxins↗
PubMed1995

The predictive value of serum progesterone and 17-OH progesterone levels on in vitro fertilization outcome.

PURPOSE: In order to identify parameters which predict prognosis for success with in vitro fertilization, 17-hydroxyprogesterone and progesterone levels were evaluated in 254 patients undergoing 296 in vitro fertilization cycles. Selected response and outcome data were recorded. RESULTS: Patients with intermediate values of serum progesterone (0.7-0.8 ng/ml) at the time of human chorionic gonadotropin administration achieved significantly higher pregnancy rates than patients with lower (< 0.7 ng/ml) or higher (> 0.8 ng/ml) levels. The clinical pregnancy rates were 46%, 31%, and 27% respectively (P = 0.02). There was no change in 17-hydroxyprogesterone concentration which predicted a higher pregnancy rate. CONCLUSION: Excellent clinical pregnancy rates were noted in cycles with a progesterone level of 0.7-0.8 ng/ml, as well as good results in cycles above 0.8 ng/ml. There is therefore no reason to administer human chorionic gonadotropin at a smaller follicle size to prevent a rise in serum progesterone.

17-alpha-Hydroxyprogesterone↗
PubMed1994

Tumor necrosis factor alpha inhibits signaling from the insulin receptor.

Insulin resistance is a common problem associated with infections and cancer and, most importantly, is the central component of non-insulin-dependent diabetes mellitus. We have recently shown that tumor necrosis factor (TNF) alpha is a key mediator of insulin resistance in animal models of non-insulin-dependent diabetes mellitus. Here, we investigate how TNF-alpha interferes with insulin action. Chronic exposure of adipocytes to low concentrations of TNF-alpha strongly inhibits insulin-stimulated glucose uptake. Concurrently, TNF-alpha treatment causes a moderate decrease in the insulin-stimulated autophosphorylation of the insulin receptor (IR) and a dramatic decrease in the phosphorylation of IR substrate 1, the major substrate of the IR in vivo. The IR isolated from TNF-alpha-treated cells is also defective in the ability to autophosphorylate and phosphorylate IR substrate 1 in vitro. These results show that TNF-alpha directly interferes with the signaling of insulin through its receptor and consequently blocks biological actions of insulin.

3T3 Cells↗
PubMed1994

Immunobiologic and biochemical properties of mutants of toxic shock syndrome toxin-1.

Toxic shock syndrome (TSS) is a multisystem illness caused mainly by Staphylococcus aureus producing TSS toxin-1 (TSST-1). A variant of TSST-1 has been isolated from ovine mastitis S. aureus. This toxin, TSST-ovine (TSST-O) is only weakly T cell mitogenic, is nonpyrogenic, does not enhance endotoxin shock, and does not cause TSS in the miniosmotic pump model. The sequence of the ovine gene (tstO) differs from the TSST-1 gene (tstH) by 14 nucleotides that change seven amino acids in the mature protein of which two are in the C-terminal half. A gene fusion containing half of both tstH and tstO was made and cloned into S. aureus. The fusion protein contained the two C-terminal amino acid differences that are in TSST-O at residues 132 and 140. The fusion protein was not T cell mitogenic and did not elicit TSS in two rabbit models. Additional experiments used mutagenesis to change the lysine residue at position 132 of TSST-O to glutamate (TSST-OK132E), as exists in TSST-1, and to change the lysine residue of the human-ovine fusion at position 132 to glutamate (TSST-11140T). Both mutants were pyrogenic, enhanced endotoxin shock, and caused TSS in the miniosmotic pump model. However, the proteins were only partially T cell mitogenic. The restoration of lethality of TSST-O and the human-ovine fusion by changing the lysine to glutamate, as exists in TSST-1, indicates that residue 132 is important in lethality. The failure to regenerate complete T cell mitogenicity of the same mutants indicates that residues 132 and 140 are important for that activity.

Amino Acid Sequence↗
PubMed1994

Screening maternal serum alpha-fetoprotein levels and human parvovirus antibodies.

The association between gestational infection with human parvovirus (B19) and fetal loss has increased interest in this virus and demand for diagnostic testing. However, serological assays for B19 are not yet widely available. Maternal serum alpha-fetoprotein (MSAFP) testing is commonly used during the second trimester to screen for various fetal defects. We attempted to determine whether an elevated level of MSAFP would be an appropriate indication for B19-specific tests. Over a 26-month period, MSAFP tests were performed at Michigan State University for 21 392 women. Sera remaining after that testing were stored frozen. Of these, 22 cases samples--from women with MSAFP levels greater than 3.0 multiples of the median (MOM) and pregnancies that ended in fetal loss--and 44 matched control samples--from women with MSAFP levels greater than 0.4 and less than 2.2 MOM and live births at term--were tested for B19 antibodies. None of the 66 samples was IgM positive, while 33 (50 per cent) were IgG positive. The presence of IgG was not significantly associated with case or control status (matched odds ratio = 0.77, 95 per cent confidence interval 0.28-2.11). These findings are consistent with other studies indicating prior infection in approximately half of adults and suggest that elevated screening MSAFP levels, in the absence of other evidence of B19 infection, should not prompt B19-specific testing.

Adult↗